CVE-2026-4705: WebRTC Signaling UB Firefox <149/ESR <140.9
CVE-2026-4705 Published on March 24, 2026
Undefined behavior in the WebRTC: Signaling component
Undefined behavior in the WebRTC: Signaling component. This vulnerability affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
Vulnerability Analysis
CVE-2026-4705 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
Reliance on Undefined, Unspecified, or Implementation-Defined Behavior
The software uses an API function, data structure, or other entity in a way that relies on properties that are not always guaranteed to hold for that entity. This can lead to resultant weaknesses when the required properties change, such as when the software is ported to a different platform or if an interaction error (CWE-435) occurs.
Products Associated with CVE-2026-4705
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Affected Versions
Mozilla Firefox:- Version unspecified and below 149 is affected.
- Version unspecified and below 140.9 is affected.
- Version unspecified and below 149 is affected.
- Version unspecified and below 140.9 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.