CVE-2026-41431Public exploitNetwork attack vector

Code execution via unsigned automatic updates

Published May 11, 2026 · Updated May 11, 2026

Improper signature verification in Zen Browser before 1.19.9b allows attackers to execute code through unsigned automatic updates. The org.mozilla.updater binary was built with --enable-unverified-updates, so it accepts MAR packages without cryptographic signatures or a bound channel identifier. Exploitation requires compromise of the update server or release pipeline; a matching SHA-512 hash is checked, but attacker-supplied code then runs on affected clients.

CVSS severity8.0
High
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in Zen Browser before 1.19.9b allows attackers to execute code through unsigned automatic updates. The org.mozilla.updater binary was built with --enable-unverified-updates, so it accepts MAR packages without cryptographic signatures or a bound channel identifier. Exploitation requires compromise of the update server or release pipeline; a matching SHA-512 hash is checked, but attacker-supplied code then runs on affected clients.

The record

CVE
CVE-2026-41431
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Zen Browser
Product
Zen Browser
Classifications
CWE-347, T1195.002
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.19.9b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Zen Browser · Zen Browserversion=< 1.19.9b

Published CVSS scores

8.0GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1195.002Compromise Software Supply Chain

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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