CVE-2026-74990CWE-119

CVE-2026-74990

Critical · published August 18, 2026

CVSS v3.1
9.8
EPSS
1%
Percentile
53.2
In the wild
Unconfirmed
What it is

Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and 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, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

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
0.00715 · 53.2th percentile
Weakness
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer
Published
2026-08-18T17:17Z
Affected products (5)
ProductVersionsFixed in
mozilla/firefox< 115.39.0115.39.0
mozilla/firefox≥ 116.0, < 140.14.0140.14.0
mozilla/firefox≥ 141.0, < 153.1.0153.1.0
mozilla/thunderbird< 140.14.0140.14.0
mozilla/thunderbird≥ 141.0, < 153.1.0153.1.0
References (9)
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045762%2C2052401%2C2058208 · [email protected]https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045774%2C2048490%2C2050864%2C2053159%2C2053260%2C2053261%2C2053582%2C2053599%2C2053607%2C2053608%2C2053853%2C2054626%2C2054627%2C2054635%2C2054677%2C2054740%2C2054832%2C2056792%2C2057098%2C2057100%2C2057101%2C2057103%2C2057117%2C2057118%2C2058048%2C2058049%2C2058622%2C2058623%2C2058665%2C2058666%2C2059121%2C2059164%2C2059188 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-74/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-75/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-76/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-77/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-78/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-79/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-80/ · [email protected]
EPSS history
Timeline
  • 18 AUG 12:23Z
    Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154
    cvelistv5