CVE-2026-74989CWE-119

CVE-2026-74989

Critical · published August 18, 2026

CVSS v3.1
9.8
EPSS
1%
Percentile
46.4
In the wild
Unconfirmed
What it is

Internally found bugs present in Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00570 · 46.4th percentile
Weakness
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer
Published
2026-08-18T17:17Z
Affected products (2)
ProductVersionsFixed in
mozilla/firefox< 154.0.0154.0.0
mozilla/thunderbird< 154.0154.0
References (4)
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2022257%2C2027351%2C2027380%2C2029289 · [email protected]https://bugzilla.mozilla.org/buglist.cgi?bug_id=2027388%2C2029750%2C2029794%2C2043298%2C2045126%2C2049810%2C2051741 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-74/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-78/ · [email protected]
EPSS history
Timeline
  • 18 AUG 12:23Z
    Internally found bugs fixed in Firefox 154
    cvelistv5