What’s Vulnerable › Vulnerabilities

CVE-2021-29961

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-24 · updated 2026-06-17
• Weakness: CWE-863

Description

When styling and rendering an oversized `<select>` element, Firefox did not apply correct clipping which allowed an attacker to paint over the user interface. This vulnerability affects Firefox < 89.

Affected products

• Mozilla Firefox: from 78.11.0 before 89.0 — fixed in 89.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 89.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1700235
• https://security.gentoo.org/glsa/202107-09
• https://www.mozilla.org/security/advisories/mfsa2021-23/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1700235
• https://security.gentoo.org/glsa/202107-09
• https://www.mozilla.org/security/advisories/mfsa2021-23/

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