CVE-2026-74990

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.53% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 42.7% of scored records. A rank, not a probability.

NVD base score

9.8 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-09-01.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-08-18 12:23Z17 DAYS AGO

Last updated

2026-09-01 21:25Z3 DAYS AGO

Reserved

2026-08-17

Assigning CNA

mozilla

Record state

PUBLISHED

Severity

Critical (CVSS 9.8)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferClass

Data version

5.2

Document digest

6ea96aceb185f4d65c6a8c40db96c3f36e819dfd1f70d2e655e71d886d0e7fda

• bugzilla.mozilla.orgModerate Severity internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045762%2C2052401%2C2058208
• bugzilla.mozilla.orgHigh Severity internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154https://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
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-74/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-75/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-76/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-77/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-78/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-79/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-80/