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CVE-2026-8946

HIGH 7.5

Published 2026-05-19 · Last modified 2026-06-30

Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

ELEVATED IMPACT

Severe if exploited (CVSS 7.5), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.6%chance of exploitation in 30 days · 42nd percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

7.5CVSS 3.1 · HIGH

  • ConfidentialityHigh
  • IntegrityNone
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Affected

Vendors Mozilla Red Hat

Products Firefox Thunderbird Red Hat Enterprise Linux Server (V. 7 Els) Red Hat Enterprise Linux Appstream Eus (V. 10.0) Red Hat Enterprise Linux Appstream (V. 10) Red Hat Enterprise Linux Appstream (V. 8) Red Hat Enterprise Linux Appstream Aus (V.8.4) Red Hat Enterprise Linux Appstream Eus Extension (V.8.4)

Weakness (CWE)

  • CWE-119: Memory buffer overflow
  • CWE-787: Out-of-bounds write

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS