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CVE-2026-75874

CRITICAL 10

Published 2026-08-18 · Last modified 2026-08-18

Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154 and Thunderbird 154.

ELEVATED IMPACT

Severe if exploited (CVSS 10), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 34th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

10CVSS 3.1 · CRITICAL

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

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

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-75874/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-75874/poc.json

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:N/S:C/C:H/I:H/A:H

Known Affected Software Configurations

VendorProductVersion range
MozillaFirefox< 154.0.0
MozillaThunderbird< 154.0

All CVSS metrics

  • CRITICAL 10 v3.1 · ADP Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
  • CRITICAL 10 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS