Integer Overflow Vulnerability in Networking Component of Firefox
CVE-2026-8956

9.8CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
19 May 2026

What is CVE-2026-8956?

A vulnerability exists within the Networking: JAR component of Firefox due to integer overflow, which could lead to unexpected behavior or potential code execution. This issue affects versions of Firefox prior to 151 and Firefox Extended Support Release (ESR) versions prior to 140.11. Users are encouraged to update their browser to the latest versions to mitigate potential risks associated with this vulnerability.

Affected Version(s)

Firefox 140.11

Firefox 151

Thunderbird 140.11

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2032427
https://www.mozilla.org/security/advisories/mfsa2026-46/
https://www.mozilla.org/security/advisories/mfsa2026-48/

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Yaqoub Aldurayhim
.