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CVE-2026-92018

CRITICAL 9.6 ALL-YEARS

Published 2026-09-15 · Last modified 2026-09-20 · mozilla · NVD: Analyzed

Sandbox escape in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

ELEVATED IMPACT

Severe if exploited (CVSS 9.6), but no confirmed exploitation. Patch on a normal cadence.

Exploitation likelihood

0.3%chance of exploitation in 30 days · 24th percentile

○ In CISA KEV○ Public exploit / PoC◆ SSVC: exploitation none, automatable no

Impact if exploited

9.6CVSS 3.1 · CRITICAL · ADP

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ⚠User interaction: A user must take an action (click / open a file)
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

No public exploit or proof-of-concept code is catalogued for this CVE (no ExploitDB, Nuclei, or CISA-KEV entry). It may still exist — search GitHub or check the references below.

Affected

Vendors Mozilla

Products Firefox Thunderbird

Weakness (CWE)

  • CWE-693: Protection Mechanism Failure

CVSS vector

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

Known Affected Software Configurations

VendorProductVersion range
MozillaFirefox< 115.41.0
MozillaFirefox≥ 116.0 and < 140.16.0
MozillaFirefox≥ 141.0 and < 153.3.0
MozillaFirefox≥ 154.0.0 and < 156.0.0
MozillaThunderbird< 140.16.0
MozillaThunderbird≥ 141.0 and < 153.3.0
MozillaThunderbird≥ 154.0 and < 156.0

All CVSS metrics

  • CRITICAL 9.6 v3.1 · ADP Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
  • CRITICAL 9.6 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS