{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-34610", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-03-30T17:15:52.500Z", "datePublished": "2026-04-02T17:54:53.250Z", "dateUpdated": "2026-04-03T17:25:10.195Z"}, "containers": {"cna": {"title": "leancrypto: Integer truncation in X.509 name parser enables certificate identity impersonation", "problemTypes": [{"descriptions": [{"cweId": "CWE-681", "lang": "en", "description": "CWE-681: Incorrect Conversion between Numeric Types", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.9, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4gr", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4gr"}, {"name": "https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a", "tags": ["x_refsource_MISC"], "url": "https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a"}, {"name": "https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1", "tags": ["x_refsource_MISC"], "url": "https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1"}], "affected": [{"vendor": "smuellerDD", "product": "leancrypto", "versions": [{"version": "< 1.7.1", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-04-02T17:54:53.250Z"}, "descriptions": [{"lang": "en", "value": "The leancrypto library is a cryptographic library that exclusively contains only PQC-resistant cryptographic algorithms. Prior to version 1.7.1, lc_x509_extract_name_segment() casts size_t vlen to uint8_t when storing the Common Name (CN) length. An attacker who crafts a certificate with CN = victim's CN + 256 bytes padding gets cn_size = (uint8_t)(256 + N) = N, where N is the victim's CN length. The first N bytes of the attacker's CN are the victim's identity. After parsing, the attacker's certificate has an identical CN to the victim's \u2014 enabling identity impersonation in PKCS#7 verification, certificate chain matching, and code signing. This issue has been patched in version 1.7.1."}], "source": {"advisory": "GHSA-636g-jxv4-v4gr", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-04-03T17:03:26.975851Z", "id": "CVE-2026-34610", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-03T17:25:10.195Z"}}]}}

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{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:leancrypto:leancrypto:*:*:*:*:*:*:*:*", "matchCriteriaId": "EEBE3140-06FC-43FD-B7D3-D96E65CD4B38", "versionEndExcluding": "1.7.1", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "The leancrypto library is a cryptographic library that exclusively contains only PQC-resistant cryptographic algorithms. Prior to version 1.7.1, lc_x509_extract_name_segment() casts size_t vlen to uint8_t when storing the Common Name (CN) length. An attacker who crafts a certificate with CN = victim's CN + 256 bytes padding gets cn_size = (uint8_t)(256 + N) = N, where N is the victim's CN length. The first N bytes of the attacker's CN are the victim's identity. After parsing, the attacker's certificate has an identical CN to the victim's \u2014 enabling identity impersonation in PKCS#7 verification, certificate chain matching, and code signing. This issue has been patched in version 1.7.1."}], "id": "CVE-2026-34610", "lastModified": "2026-04-24T13:01:10.780", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.9, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-04-02T18:16:32.567", "references": [{"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a"}, {"source": "security-advisories@github.com", "tags": ["Product", "Release Notes"], "url": "https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1"}, {"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4gr"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-681"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.7.1)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "cna", "scores": [{"score": 100.0, "source": "cna"}]}, "original": {"product": "leancrypto", "source": "cna", "vendor": "smuellerDD"}, "product": "leancrypto", "vendor": "smuellerdd"}], "analysis": {"en": {"generated_at": "2026-04-02T22:27:44.290913+00:00", "value": {"mitigation_remediation": ["Apply the official patch by upgrading leancrypto to version 1.7.1 or later."], "summary": {"action": "Immediate Patch", "impact": "Certificate Identity Impersonation"}, "threat_synthesis": {"affected_systems": "Products: leancrypto library by smuellerDD. Versions before v1.7.1 are affected. The CVE affects any deployment of leancrypto that performs X.509 CN parsing.\n", "description_and_impact": "The vulnerable function in leancrypto cast a size_t length to a uint8_t when storing the Common Name length in a certificate. An attacker can supply a CN field that is 256 bytes longer than the victim\u2019s CN. Because the high byte is truncated, the parsed length wraps to the victim\u2019s CN length and the first N bytes of the attacker\u2019s CN match the victim\u2019s name. The resulting certificate appears to have the victim\u2019s identity, allowing an attacker to forge PKCS#7 signatures, bypass certificate chain matching, or sign code that will be trusted as the victim.\n\nThe weakness is an integer truncation error controlled by attacker\u2011supplied certificate data, creating the possibility of certificate impersonation.\n\nThe exploit requires constructing a malicious certificate; the attacker can embed this certificate in any PKCS#7 or code\u2011signing workflow that relies on leancrypto for name parsing. The risk is limited to environments that use this library for certificate handling, and the impact is on confidentiality and integrity of signed data.\n\nAffected systems are those using smuellerDD:leancrypto prior to version 1.7.1. The patch was applied in v1.7.1, restoring proper size handling for CN lengths.\n\nSeverity is moderate with a CVSS score of 5.9, no EPSS data is available, and the vulnerability is not listed in CISA\u2019s KEV catalog. The likely attack vector is a crafted certificate presented to an application that uses leancrypto for verification.\n", "risk_and_exploitability": "The CVSS score of 5.9 indicates moderate risk. Exploitation requires the attacker to create a certificate with a Common Name padded by 256 bytes, which can be done offline. Because the vulnerability is only in name parsing, lateral movement or system compromise requires the attacker to force certificate verification in the target application. No public exploits are known, and the vulnerability is not catalogued in KEV. However, the ability to impersonate a certificate authority or sign code means potential for significant damage if the library is used in security-sensitive contexts.\n"}}}}, "created": "2026-04-03T07:32:08.240684+00:00", "updated": "2026-04-03T09:17:09.328557+00:00", "vendors": ["smuellerdd", "smuellerdd$PRODUCT$leancrypto"]}