CVE-2026-8961

MEDIUM

Published May 19, 2026 Modified May 20, 2026 CWE-290

Description

Spoofing issue in the Form Autofill component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS v3.1 Score

6.5

MEDIUM

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

EPSS — Exploit Prediction

0.0003

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-290 CWE-290

Affected Products

Vendor	Product	Versions
mozilla	firefox	< 140.11.0
mozilla	firefox	< 151.0.0
mozilla	thunderbird	< 140.11
mozilla	thunderbird	< 151.0.0

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2026-46/ https://www.mozilla.org/security/advisories/mfsa2026-48/ https://www.mozilla.org/security/advisories/mfsa2026-50/ https://www.mozilla.org/security/advisories/mfsa2026-51/

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=1962625

Frequently Asked Questions

What is CVE-2026-8961? +

Spoofing issue in the Form Autofill component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-8961? +

CVE-2026-8961 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0003, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-8961? +

CVE-2026-8961 affects products from mozilla, specifically: firefox, thunderbird. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-8961? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-6213

A vulnerability in Remote Spark SparkView before build 1122 allows an attacker to bypasses the local connection check and achieve …

CVE-2025-22271

The application or its infrastructure allows for IP address spoofing by providing its own value in the "X-Forwarded-For" header. Thus, …

CVE-2025-31122

scratch-coding-hut.github.io is the website for Coding Hut. In 1.0-beta3 and earlier, the login link can be used to login to …

CVE-2025-46345

Auth0 Account Link Extension is an extension aimed to help link accounts easily. Versions 2.3.4 to 2.6.6 do not verify …

CVE-2025-34053

An authentication bypass vulnerability exists in AVTECH IP camera, DVR, and NVR devices’ streamd web server. The strstr() function is …

CVE-2025-34063

A cryptographic authentication bypass vulnerability exists in OneLogin AD Connector prior to 6.1.5 due to the exposure of a tenant’s …

Quick Facts

CVSS Score: 6.5
Severity: MEDIUM
EPSS: 0.0003
Published: May 19, 2026

Scan for this vulnerability

Check if your website or infrastructure is affected by CVE-2026-8961.

Website Scan Port Scan

Browse CVEs

Critical High CISA KEV ! Most likely exploited →