Vulnerability in Mozilla Thunderbird
CVE-2026-92238
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.
Vulnerability class: HTTP Request Smuggling
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (45.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-95/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-94/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-96/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-92238?
- CVE-2026-92238 is a critical-severity vulnerability in Mozilla Thunderbird, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 9.8/10. Published 2026-09-15.
- How severe is CVE-2026-92238?
- Critical severity. CVSS v3 base score is 9.8 out of 10.