Web Codecs Uninitialized Mem in Firefox <150 (Fixed 150)
CVE-2026-6748 Published on April 21, 2026
Uninitialized memory in the Audio/Video: Web Codecs component
Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
Vulnerability Analysis
CVE-2026-6748 is exploitable 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
Use of Uninitialized Variable
The code uses a variable that has not been initialized, leading to unpredictable or unintended results. In some languages such as C and C++, stack variables are not initialized by default. They generally contain junk data with the contents of stack memory before the function was invoked. An attacker can sometimes control or read these contents. In other languages or conditions, a variable that is not explicitly initialized can be given a default value that has security implications, depending on the logic of the program. The presence of an uninitialized variable can sometimes indicate a typographic error in the code.
Products Associated with CVE-2026-6748
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Affected Versions
Mozilla Firefox:- Version 140.10, <= 140.* is unaffected.
- Version 150, <= * is unaffected.
- Version 140.10, <= 140.* is unaffected.
- Version 150, <= * is unaffected.