CVE-2026-92238

Ambiguous parsing of mail headers

Published Sep 15, 2026 CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Description
A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4782-1 thunderbird security update
Debian DSA Debian DSA DSA-6503-1 thunderbird security update
History
Type Values Removed Values Added
CPEs cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Weaknesses CWE-444
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
Weaknesses CWE-119
CWE-200
Type Values Removed Values Added
Weaknesses CWE-843
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-119
CWE-200
Type Values Removed Values Added
First Time appeared Mozilla
Mozilla thunderbird
Vendors & Products Mozilla
Mozilla thunderbird
Type Values Removed Values Added
Description A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156 and Thunderbird 140.16. A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
References
Type Values Removed Values Added
Description A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 140.16. A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156 and Thunderbird 140.16.
References
Type Values Removed Values Added
Description A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 140.16.
Title Ambiguous parsing of mail headers
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Sep 22, 2026, 6:43 PM
Reserved
Sep 15, 2026, 7:42 PM
Status
Analyzed
Published
Sep 15, 2026, 8:19 PM
Modified
Sep 24, 2026, 2:15 PM
Severity
Moderate
Public date
Sep 15, 2026, 7:42 PM