CVE-2026-84144

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.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• 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

0.42% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 36.4% of scored records. A rank, not a probability.

NVD base score

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

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-09-03.

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

2026-09-01 12:19Z1 MO AGO

Last updated

2026-09-03 15:41Z1 MO AGO

Reserved

2026-09-01

Assigning CNA

mozilla

Record state

PUBLISHED

Severity

High (CVSS 7.5)

CNA CVSS vector

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

Weaknesses

• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferClass
• CWE-787Out-of-bounds WriteBase

Data version

5.2

Document digest

8482258b0a2222d0d9ff9192b5b08385d0f95207a5393233082a202cf036be72

• bugzilla.mozilla.orgModerate Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054619%2C2054620%2C2054624%2C2054702%2C2054726%2C2054775%2C2055703%2C2058006%2C2058013%2C2058098%2C2058627%2C2058661%2C2059127%2C2059128%2C2059180%2C2059199%2C2059205%2C2061320%2C2061430%2C2061495%2C2061505%2C2061532%2C2061799
• bugzilla.mozilla.orgHigh Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054625%2C2059002%2C2061775
• bugzilla.mozilla.orgLow Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054691%2C2058085%2C2059144%2C2059191%2C2059192%2C2061521%2C2062395%2C2062404
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-82/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-85/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-86/
• www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-88/