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{"bugzilla": {"description": "thunderbird: Out of bounds read in IMAP parsing", "id": "2451001", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2451001"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.2", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H", "status": "draft"}, "cwe": "CWE-130", "details": ["A flaw was found in Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:\nA malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2026-4371", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "rhel10/thunderbird-flatpak", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-03-24T20:27:15Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-4371\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-4371\nhttps://www.mozilla.org/security/advisories/mfsa2026-24/#CVE-2026-4371"], "statement": "Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.", "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,149)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Thunderbird", "source": "cna", "vendor": "Mozilla"}, "product": "thunderbird", "vendor": "mozilla"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,140.9)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Thunderbird", "source": "cna", "vendor": "Mozilla"}, "product": "thunderbird", "vendor": "mozilla"}], "analysis": {"en": {"generated_at": "2026-04-13T15:40:09.502954+00:00", "value": {"mitigation_remediation": ["Upgrade Thunderbird to version 149 on the main release or to 140.9 on the ESR branch. Once the update is applied, restart the application to complete the patch. Keep Thunderbird updated to the latest release to prevent re\u2011use of this code."], "summary": {"action": "Immediate Patch", "impact": "Out-of-bounds read during IMAP parsing leading to possible crashes or data exposure"}, "threat_synthesis": {"affected_systems": "The vulnerability affects Mozilla Thunderbird on all versions prior to 149 and the ESR branch prior to 140.9. Any user running these vulnerable Thunderbird releases is at risk when connecting to an IMAP server that can be compromised or set up to feed malformed data.", "description_and_impact": "A malicious mail server can send malformed strings with negative lengths, causing the IMAP parser to read outside its buffer. This out-of-bounds read can crash Thunderbird or expose sensitive data. The weakness is identified as CWE-126 and CWE-130, representing insecure memory handling and boundary checks.", "risk_and_exploitability": "The CVSS score of 7.4 indicates a moderate to high severity. The EPSS score is below 1%, suggesting low likelihood of widespread exploitation at present, and the vulnerability is not listed in the CISA KEV catalog. However, the attack vector is inferred to be an adversary who can control mail server content or compromise the mail server connection. Exploitation requires the victim to receive a crafted IMAP response, after which the parser may crash or expose memory. Timely patching is therefore recommended to mitigate both possible denial of service and confidentiality risks."}}}}, "created": "2026-03-25T11:45:52.312369+00:00", "updated": "2026-04-14T16:42:41.992920+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$thunderbird"]}