Same-Origin Policy Bypass in Service Workers (Firefox <154, Thunderbird <154)
CVE-2026-74956 Published on August 18, 2026
Same-origin policy bypass in the DOM: Service Workers component
Same-origin policy bypass in the DOM: Service Workers component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
Vulnerability Analysis
CVE-2026-74956 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 have a high impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is an Object Type Confusion Vulnerability?
The program allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.
CVE-2026-74956 has been classified to as an Object Type Confusion vulnerability or weakness.
Products Associated with CVE-2026-74956
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Affected Versions
Mozilla Firefox:- Version 153.1, <= 153.* is unaffected.
- Version 154, <= * is unaffected.
- Version 153.1, <= 153.* is unaffected.
- Version 154, <= * is unaffected.