What’s Vulnerable › Vulnerabilities

CVE-2026-12307: Memory safety bug fixed in Thunderbird 152

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-16 · updated 2026-10-26
• Weakness: CWE-119

Description

Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

Affected products

• Mozilla Firefox: before 140.12.0; before 152.0.0 — fixed in 140.12.0, 152.0.0
• Mozilla Thunderbird: before 140.12.0; before 152.0.0 — fixed in 140.12.0, 152.0.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 140.12.0, 152.0.0; Mozilla Thunderbird 140.12.0, 152.0.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2038133
• https://www.mozilla.org/security/advisories/mfsa2026-57/
• https://www.mozilla.org/security/advisories/mfsa2026-58/
• https://www.mozilla.org/security/advisories/mfsa2026-60/
• https://www.mozilla.org/security/advisories/mfsa2026-61/

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