Critical 10.0Published Aug 18, 2026

CVE-2026-75874Sandbox escape in the Remote Settings Client component

Updated under an hour ago (Oct 27, 2026, 10:10 AM ET)

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It affects Mozilla Firefox and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Mozilla Firefox

Exploited in the last 30 days

Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.

CVSS: 10.0 CRITICAL (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness (CWE): CWE-693
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: mozilla
NVD analysis: Modified
Record last updated: Sep 1, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Mozilla Firefox mozilla:firefox (from the name)	115.40 builds before 115.* not affected; 140.15 builds before 140.* not affected; 153.2 builds before 153.* not affected; from 154 not affected	CNA record
Mozilla Thunderbird mozilla:thunderbird (from the name)	140.15 builds before 140.* not affected; 153.2 builds before 153.* not affected; from 154 not affected	CNA record
mozilla firefox mozilla:firefox	before 154.0.0	NVD
mozilla thunderbird mozilla:thunderbird	before 154.0	NVD

References

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2039972	permissions-required
https://www.mozilla.org/security/advisories/mfsa2026-74/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-78/	vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2026-83/
https://www.mozilla.org/security/advisories/mfsa2026-84/
https://www.mozilla.org/security/advisories/mfsa2026-85/
https://www.mozilla.org/security/advisories/mfsa2026-87/
https://www.mozilla.org/security/advisories/mfsa2026-88/

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.