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CVE-2026-74981 is a site-isolation issue in the Audio/Video: Web Codecs component of Mozilla Firefox and Mozilla Thunderbird. The flaw could permit violation of browser site-isolation boundaries when processing Web Codecs functionality. Mozilla fixed the issue in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
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No public exploit code observed for this vulnerability.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
13 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Site-isolation weakness in Firefox Web Codecs.
A site-isolation flaw in Firefox Web Codecs.
A site isolation issue in Firefox's Audio/Video: Web Codecs component.
Unknown
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.