Undefined Behavior in WebRTC Signaling Component of Firefox Browser
CVE-2026-4718

8.1HIGH

Key Information:

Vendor

Mozilla
Status
Firefox
Firefox Esr
Thunderbird
Vendor
CVE Published:
24 March 2026

What is CVE-2026-4718?

The vulnerability in the WebRTC signaling component of Firefox exposes users to potential threats due to undefined behavior. Affected versions include Firefox earlier than 149 and Firefox ESR versions earlier than 140.9. Users are recommended to update their browsers to mitigate any risks associated with this issue.

Affected Version(s)

Firefox < 149

Firefox ESR < 140.9

Thunderbird < 149

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2014864
https://www.mozilla.org/security/advisories/mfsa2026-20/
https://www.mozilla.org/security/advisories/mfsa2026-22/

CVSS V3.1

Score:
8.1
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

Evyatar Ben Asher, Keane Lucas, Nicholas Carlini, Newton Cheng, Daniel Freeman, Alex Gaynor, and Joel Weinberger using Claude from Anthropic
.