{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-22977", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.935Z", "datePublished": "2026-01-21T13:08:54.858Z", "dateUpdated": "2026-05-11T21:57:36.693Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-11T21:57:36.693Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sock: fix hardened usercopy panic in sock_recv_errqueue\n\nskbuff_fclone_cache was created without defining a usercopy region,\n[1] unlike skbuff_head_cache which properly whitelists the cb[] field.\n[2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is\nenabled and the kernel attempts to copy sk_buff.cb data to userspace\nvia sock_recv_errqueue() -> put_cmsg().\n\nThe crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone()\n (from skbuff_fclone_cache) [1]\n2. The skb is cloned via skb_clone() using the pre-allocated fclone\n[3] 3. The cloned skb is queued to sk_error_queue for timestamp\nreporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE)\n5. sock_recv_errqueue() calls put_cmsg() to copy serr->ee from skb->cb\n[4] 6. __check_heap_object() fails because skbuff_fclone_cache has no\n usercopy whitelist [5]\n\nWhen cloned skbs allocated from skbuff_fclone_cache are used in the\nsocket error queue, accessing the sock_exterr_skb structure in skb->cb\nvia put_cmsg() triggers a usercopy hardening violation:\n\n[ 5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_fclone_cache' (offset 296, size 16)!\n[ 5.382796] kernel BUG at mm/usercopy.c:102!\n[ 5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n[ 5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7\n[ 5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[ 5.384903] RIP: 0010:usercopy_abort+0x6c/0x80\n[ 5.384903] Code: 1a 86 51 48 c7 c2 40 15 1a 86 41 52 48 c7 c7 c0 15 1a 86 48 0f 45 d6 48 c7 c6 80 15 1a 86 48 89 c1 49 0f 45 f3 e8 84 27 88 ff <0f> 0b 490\n[ 5.384903] RSP: 0018:ffffc900006f77a8 EFLAGS: 00010246\n[ 5.384903] RAX: 000000000000006f RBX: ffff88800f0ad2a8 RCX: 1ffffffff0f72e74\n[ 5.384903] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff87b973a0\n[ 5.384903] RBP: 0000000000000010 R08: 0000000000000000 R09: fffffbfff0f72e74\n[ 5.384903] R10: 0000000000000003 R11: 79706f6372657375 R12: 0000000000000001\n[ 5.384903] R13: ffff88800f0ad2b8 R14: ffffea00003c2b40 R15: ffffea00003c2b00\n[ 5.384903] FS: 0000000011bc4380(0000) GS:ffff8880bf100000(0000) knlGS:0000000000000000\n[ 5.384903] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 5.384903] CR2: 000056aa3b8e5fe4 CR3: 000000000ea26004 CR4: 0000000000770ef0\n[ 5.384903] PKRU: 55555554\n[ 5.384903] Call Trace:\n[ 5.384903] <TASK>\n[ 5.384903] __check_heap_object+0x9a/0xd0\n[ 5.384903] __check_object_size+0x46c/0x690\n[ 5.384903] put_cmsg+0x129/0x5e0\n[ 5.384903] sock_recv_errqueue+0x22f/0x380\n[ 5.384903] tls_sw_recvmsg+0x7ed/0x1960\n[ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5.384903] ? schedule+0x6d/0x270\n[ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5.384903] ? mutex_unlock+0x81/0xd0\n[ 5.384903] ? __pfx_mutex_unlock+0x10/0x10\n[ 5.384903] ? __pfx_tls_sw_recvmsg+0x10/0x10\n[ 5.384903] ? _raw_spin_lock_irqsave+0x8f/0xf0\n[ 5.384903] ? _raw_read_unlock_irqrestore+0x20/0x40\n[ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5\n\nThe crash offset 296 corresponds to skb2->cb within skbuff_fclones:\n - sizeof(struct sk_buff) = 232 - offsetof(struct sk_buff, cb) = 40 -\n offset of skb2.cb in fclones = 232 + 40 = 272 - crash offset 296 =\n 272 + 24 (inside sock_exterr_skb.ee)\n\nThis patch uses a local stack variable as a bounce buffer to avoid the hardened usercopy check failure.\n\n[1] https://elixir.bootlin.com/linux/v6.12.62/source/net/ipv4/tcp.c#L885\n[2] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5104\n[3] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5566\n[4] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5491\n[5] https://elixir.bootlin.com/linux/v6.12.62/source/mm/slub.c#L5719"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/sock.c"], "versions": [{"version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "lessThan": "88dd6be7ebb3153b662c2cebcb06e032a92857f5", "status": "affected", "versionType": "git"}, {"version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "lessThan": "c655d2167bf014d4c61b4faeca59b60ff9b9f6b1", "status": "affected", "versionType": "git"}, {"version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "lessThan": "8c6901aa29626e35045130bac09b75f791acca85", "status": "affected", "versionType": "git"}, {"version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "lessThan": "582a5e922a9652fcbb7d0165c95d5b20aa37575d", "status": "affected", "versionType": "git"}, {"version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "lessThan": "005671c60fcf1dbdb8bddf12a62568fd5e4ec391", "status": "affected", "versionType": "git"}, {"version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "lessThan": "e00b169eaac5f7cdbf710c354c8fa76d02009115", "status": "affected", "versionType": "git"}, {"version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "lessThan": "2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/sock.c"], "versions": [{"version": "4.16", "status": "affected"}, {"version": "0", "lessThan": "4.16", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.248", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.198", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.161", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.121", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.66", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.6", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "5.10.248"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "5.15.198"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.1.161"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.6.121"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.12.66"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.18.6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.19"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/88dd6be7ebb3153b662c2cebcb06e032a92857f5"}, {"url": "https://git.kernel.org/stable/c/c655d2167bf014d4c61b4faeca59b60ff9b9f6b1"}, {"url": "https://git.kernel.org/stable/c/8c6901aa29626e35045130bac09b75f791acca85"}, {"url": "https://git.kernel.org/stable/c/582a5e922a9652fcbb7d0165c95d5b20aa37575d"}, {"url": "https://git.kernel.org/stable/c/005671c60fcf1dbdb8bddf12a62568fd5e4ec391"}, {"url": "https://git.kernel.org/stable/c/e00b169eaac5f7cdbf710c354c8fa76d02009115"}, {"url": "https://git.kernel.org/stable/c/2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20"}], "title": "net: sock: fix hardened usercopy panic in sock_recv_errqueue", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "28823BF6-2E21-40F0-9BF2-FB2E3202B725", "versionEndExcluding": "5.10.248", "versionStartIncluding": "4.16", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "82159CAA-B6BA-43C6-85D8-65BDBC175A7E", "versionEndExcluding": "5.15.198", "versionStartIncluding": "5.11", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "E135B7E2-61FC-4DC1-8570-ABD67894FFDE", "versionEndExcluding": "6.1.161", "versionStartIncluding": "5.16", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "BB7A164B-7422-4A1C-82FB-5FCAEE53C06C", "versionEndExcluding": "6.6.121", "versionStartIncluding": "6.2", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "F72B884C-B44F-40E4-9895-CE421AC663D0", "versionEndExcluding": "6.12.66", "versionStartIncluding": "6.7", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "879529BC-5B4C-4EBE-BF1D-1A31404A8B2E", "versionEndExcluding": "6.18.6", "versionStartIncluding": "6.13", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc1:*:*:*:*:*:*", "matchCriteriaId": "17B67AA7-40D6-4AFA-8459-F200F3D7CFD1", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc2:*:*:*:*:*:*", "matchCriteriaId": "C47E4CC9-C826-4FA9-B014-7FE3D9B318B2", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc3:*:*:*:*:*:*", "matchCriteriaId": "F71D92C0-C023-48BD-B3B6-70B638EEE298", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc4:*:*:*:*:*:*", "matchCriteriaId": "13580667-0A98-40CC-B29F-D12790B91BDB", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sock: fix hardened usercopy panic in sock_recv_errqueue\n\nskbuff_fclone_cache was created without defining a usercopy region,\n[1] unlike skbuff_head_cache which properly whitelists the cb[] field.\n[2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is\nenabled and the kernel attempts to copy sk_buff.cb data to userspace\nvia sock_recv_errqueue() -> put_cmsg().\n\nThe crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone()\n (from skbuff_fclone_cache) [1]\n2. The skb is cloned via skb_clone() using the pre-allocated fclone\n[3] 3. The cloned skb is queued to sk_error_queue for timestamp\nreporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE)\n5. sock_recv_errqueue() calls put_cmsg() to copy serr->ee from skb->cb\n[4] 6. __check_heap_object() fails because skbuff_fclone_cache has no\n usercopy whitelist [5]\n\nWhen cloned skbs allocated from skbuff_fclone_cache are used in the\nsocket error queue, accessing the sock_exterr_skb structure in skb->cb\nvia put_cmsg() triggers a usercopy hardening violation:\n\n[ 5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_fclone_cache' (offset 296, size 16)!\n[ 5.382796] kernel BUG at mm/usercopy.c:102!\n[ 5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n[ 5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7\n[ 5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[ 5.384903] RIP: 0010:usercopy_abort+0x6c/0x80\n[ 5.384903] Code: 1a 86 51 48 c7 c2 40 15 1a 86 41 52 48 c7 c7 c0 15 1a 86 48 0f 45 d6 48 c7 c6 80 15 1a 86 48 89 c1 49 0f 45 f3 e8 84 27 88 ff <0f> 0b 490\n[ 5.384903] RSP: 0018:ffffc900006f77a8 EFLAGS: 00010246\n[ 5.384903] RAX: 000000000000006f RBX: ffff88800f0ad2a8 RCX: 1ffffffff0f72e74\n[ 5.384903] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff87b973a0\n[ 5.384903] RBP: 0000000000000010 R08: 0000000000000000 R09: fffffbfff0f72e74\n[ 5.384903] R10: 0000000000000003 R11: 79706f6372657375 R12: 0000000000000001\n[ 5.384903] R13: ffff88800f0ad2b8 R14: ffffea00003c2b40 R15: ffffea00003c2b00\n[ 5.384903] FS: 0000000011bc4380(0000) GS:ffff8880bf100000(0000) knlGS:0000000000000000\n[ 5.384903] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 5.384903] CR2: 000056aa3b8e5fe4 CR3: 000000000ea26004 CR4: 0000000000770ef0\n[ 5.384903] PKRU: 55555554\n[ 5.384903] Call Trace:\n[ 5.384903] <TASK>\n[ 5.384903] __check_heap_object+0x9a/0xd0\n[ 5.384903] __check_object_size+0x46c/0x690\n[ 5.384903] put_cmsg+0x129/0x5e0\n[ 5.384903] sock_recv_errqueue+0x22f/0x380\n[ 5.384903] tls_sw_recvmsg+0x7ed/0x1960\n[ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5.384903] ? schedule+0x6d/0x270\n[ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5.384903] ? mutex_unlock+0x81/0xd0\n[ 5.384903] ? __pfx_mutex_unlock+0x10/0x10\n[ 5.384903] ? __pfx_tls_sw_recvmsg+0x10/0x10\n[ 5.384903] ? _raw_spin_lock_irqsave+0x8f/0xf0\n[ 5.384903] ? _raw_read_unlock_irqrestore+0x20/0x40\n[ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5\n\nThe crash offset 296 corresponds to skb2->cb within skbuff_fclones:\n - sizeof(struct sk_buff) = 232 - offsetof(struct sk_buff, cb) = 40 -\n offset of skb2.cb in fclones = 232 + 40 = 272 - crash offset 296 =\n 272 + 24 (inside sock_exterr_skb.ee)\n\nThis patch uses a local stack variable as a bounce buffer to avoid the hardened usercopy check failure.\n\n[1] https://elixir.bootlin.com/linux/v6.12.62/source/net/ipv4/tcp.c#L885\n[2] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5104\n[3] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5566\n[4] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5491\n[5] https://elixir.bootlin.com/linux/v6.12.62/source/mm/slub.c#L5719"}], "id": "CVE-2026-22977", "lastModified": "2026-02-26T20:02:55.910", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2026-01-21T14:16:06.853", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/005671c60fcf1dbdb8bddf12a62568fd5e4ec391"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/582a5e922a9652fcbb7d0165c95d5b20aa37575d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/88dd6be7ebb3153b662c2cebcb06e032a92857f5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/8c6901aa29626e35045130bac09b75f791acca85"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c655d2167bf014d4c61b4faeca59b60ff9b9f6b1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e00b169eaac5f7cdbf710c354c8fa76d02009115"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-476"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: net: sock: fix hardened usercopy panic in sock_recv_errqueue", "id": "2431602", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2431602"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-489", "details": ["No description is available for this CVE."], "name": "CVE-2026-22977", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-01-21T13:08:54Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-22977\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-22977\nhttps://git.kernel.org/stable/c/005671c60fcf1dbdb8bddf12a62568fd5e4ec391\nhttps://git.kernel.org/stable/c/2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20\nhttps://git.kernel.org/stable/c/582a5e922a9652fcbb7d0165c95d5b20aa37575d\nhttps://git.kernel.org/stable/c/88dd6be7ebb3153b662c2cebcb06e032a92857f5\nhttps://git.kernel.org/stable/c/8c6901aa29626e35045130bac09b75f791acca85\nhttps://git.kernel.org/stable/c/c655d2167bf014d4c61b4faeca59b60ff9b9f6b1\nhttps://git.kernel.org/stable/c/e00b169eaac5f7cdbf710c354c8fa76d02009115"], "threat_severity": "Moderate"}

{"analysis": {"en": {"generated_at": "2026-04-18T04:17:15.156802+00:00", "value": {"mitigation_remediation": ["Update the kernel to a version where the fclone cache usercopy issue is fixed (e.g., Linux 6.12.62 or newer).", "If a patch is unavailable, recompile the kernel without CONFIG_HARDENED_USERCOPY to disable the hardened usercopy mechanism that triggers the crash.", "As a temporary measure, limit or review applications that consume socket error queues with MSG_ERRQUEUE to reduce the surface for triggering the bug."], "summary": {"action": "Apply patch", "impact": "Kernel crash (Denial of Service)"}, "threat_synthesis": {"affected_systems": "The issue affects Linux kernel releases that use the fclone cache and have CONFIG_HARDENED_USERCOPY enabled, including the 6.12 series and earlier 6.19 release candidates. Any distribution or customized kernel containing those components is potentially vulnerable if the patched code has not been applied.", "description_and_impact": "A flaw in the Linux kernel\u2019s skbuff_fclone_cache routine allows a hardened usercopy vulnerability when user space reads a socket error queue. When CONFIG_HARDENED_USERCOPY is enabled, the kernel copies the skb->cb field to userspace via sock_recv_errqueue() -> put_cmsg(). Because skbuff_fclone_cache lacks a proper whitelist, this triggers a usercopy hardening check failure, causing a BUG() and kernel panic. The result is loss of system availability and a potential crash of the affected process. The weakness maps to input validation and untrusted data handling, reflected in CWE\u2011476 and CWE\u2011489.", "risk_and_exploitability": "The CVSS score is 5.5, indicating moderate severity, while the EPSS score is below 1%, reflecting a low likelihood of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires a userspace program that can manipulate TCP sockets to generate error queue entries and trigger the bug, which can be done locally or over a network if the system accepts crafted packets. An attacker who succeeds can force a kernel panic, temporarily or permanently disrupting service. The low EPSS suggests that widespread, automated attacks are unlikely, but targeted or zero\u2011day exploitation could still be feasible if an attacker gains sufficient interaction with the vulnerable socket stack."}}}}, "created": "2026-04-18T04:30:35.822416+00:00", "updated": "2026-04-18T04:30:35.822463+00:00", "vendors": []}