What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 10.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-18 · updated 2026-09-01
• Weakness: CWE-693

Description

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.

Affected products

• Mozilla Firefox: before 154.0.0 — fixed in 154.0.0
• Mozilla Thunderbird: before 154.0 — fixed in 154.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 154.0.0; Mozilla Thunderbird 154.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2039972
• https://www.mozilla.org/security/advisories/mfsa2026-74/
• https://www.mozilla.org/security/advisories/mfsa2026-78/
• 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/

Get alerted when CVE-2026-75874 or the next vulnerability affects your stack