Use-After-Free Vulnerability in Mozilla Firefox Products
CVE-2026-12291

8.8HIGH

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
16 June 2026

What is CVE-2026-12291?

A use-after-free vulnerability has been identified in the Networking component of Mozilla Firefox, which could allow attackers to manipulate memory. This issue can lead to potential exploitation through crafted HTTP requests. Mozilla has provided fixes in Firefox version 152 and the Extended Support Releases (ESR) 140.12 and 115.37. Users are encouraged to update their browsers to ensure the integrity and security of their online activities.

Affected Version(s)

Firefox 115.37

Firefox 140.12

Firefox 152

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2036929
https://www.mozilla.org/security/advisories/mfsa2026-57/
https://www.mozilla.org/security/advisories/mfsa2026-58/

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Zijie Zhao
.