CVE-2026-4371
Last modified
CVE-2026-4371 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. A 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. EPSS estimates a 0.29% chance of exploitation in the next 30 days.
Description
A 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. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | < 140.9.0 |
| Mozilla | Thunderbird | < 149.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2023493Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-23/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-24/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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