Description
A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by sending an untagged '* ID' response, crashing Thunderbird. The affected parsing path is reachable before authentication. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
Affected products
mozilla: thunderbird
References4
- www.mozilla.org/security/advisories/mfsa2026-94/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-95/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-96/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=2069113 Permissions Required
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H - EPSS — exploit probability
- 1% percentile: 50 · as of 7 November 2026
- CWE
- CWE-125
Could this be exploited in your environment?
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