CVE-2026-41431HIGH 8.0EPSS p9.8%

CVE-2026-41431CVE-2026-41431

Description

Zen is a firefox-based browser. Prior to 1.19.9b, Zen Browser ships a Mozilla Application Resource (MAR) updater (org.mozilla.updater) that has had all MAR signature verification stripped from the Firefox codebase it was forked from. The MAR files served to users contain zero cryptographic signatures, and the updater binary contains zero cryptographic verification code. This eliminates the defense-in-depth that MAR signing provides. If the update server or GitHub release pipeline is compromised, arbitrary unsigned code can be delivered to all Zen users via the auto-update mechanism. This vulnerability is fixed in 1.19.9b.

Scoring

CVSS 3.18.0 (HIGH)
VectorCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
EPSS0.20% probability of exploitation · percentile 9.8% · 2026-06-18T12:00:27Z
Published2026-05-11
Last modified2026-05-13

Underlying weaknesses· 1

CWE-347

References

  1. https://github.com/zen-browser/desktop/commit/270db6d6713d2c6c14d9df0b4bc7662843d3d54e
  2. https://github.com/zen-browser/desktop/security/advisories/GHSA-qpj9-m8jc-mw6q
  3. https://github.com/zen-browser/desktop/security/advisories/GHSA-qpj9-m8jc-mw6q

1

TypeTargetConfidenceTier
WeaknessImproper Verification of Cryptographic Signaturecwe-3470%live

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Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.