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9.1

Firefox and Thunderbird allow remote settings bypass

CVE-2026-92038 · published 1 month ago
Summary

The Remote Settings feature in Firefox and Thunderbird can be tricked into ignoring security protections, potentially letting attackers change settings without permission. This affects current versions of Firefox and Thunderbird on all platforms. Updating to Firefox 156 or later, Firefox ESR 153.3 or later, and Thunderbird 156 or later (or 153.3 for ESR) resolves the issue.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
Ecosystem VendorProductAffected versions
– mozilla firefox All versions
Debian:14 debian thunderbird All versions
– mozilla thunderbird All versions
Ubuntu:18.04:LTS canonical mozjs52 All versions
Ubuntu:18.04:LTS canonical mozjs38 All versions
Ubuntu:20.04:LTS canonical mozjs68 All versions
Ubuntu:22.04:LTS canonical mozjs102 All versions
Ubuntu:22.04:LTS canonical mozjs78 All versions
Ubuntu:22.04:LTS canonical mozjs91 All versions
Ubuntu:22.04:LTS canonical thunderbird All versions
Ubuntu:24.04:LTS canonical mozjs115 All versions
Original advisory text
Mitigation bypass in the Remote Settings Client component
Mitigation bypass in the Remote Settings Client component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.
References
Fix within
Internet-facing 3 days
Internal 60 days
  • Not known to be exploited
  • Can be exploited automatically
  • Gives an attacker full control
Severity
9.1 Critical
Exploitation
<1% chance of attack within 30 days
Type
CWE-693Protection Mechanism Failure
Timeline
Published15 Sep 2026
Updated31 Oct 2026
First seen15 Sep 2026
Sources
CVE-2026-92038 · NVD
CVE-2026-92038 · MITRE
UBUNTU-CVE-2026-92038 · OSV
DEBIAN-CVE-2026-92038 · OSV
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