Is CVE-2026-41431 in the CISA KEV catalog?

No. CVE-2026-41431 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-41431?

CVE-2026-41431 has a CVSS v3 base score of 8.0 (HIGH).

What is the EPSS score for CVE-2026-41431?

CVE-2026-41431 has an EPSS score of 0.20% (10th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-41431?

No published fix for CVE-2026-41431 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-41431

HIGH

8.0

CVSS v3

NVD

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.

CWE-347

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredHigh

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Exploit Intelligence

0.20%probability of exploitation in 30 days

10thpercentile

Low risk: more likely to be exploited than 10% of all known CVEs.

References

Other references2

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-13.