What’s Vulnerable › Vulnerabilities

CVE-2021-29953

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% 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-79

Description

A malicious webpage could have forced a Firefox for Android user into executing attacker-controlled JavaScript in the context of another domain, resulting in a Universal Cross-Site Scripting vulnerability. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected. Further details are being temporarily withheld to allow users an opportunity to update.*. This vulnerability affects Firefox < 88.0.1 and Firefox for Android < 88.1.3.

Affected products

• Mozilla Firefox: before 88.0.1; before 88.1.3 — fixed in 88.0.1, 88.1.3

How to fix

Upgrade to a fixed version: Mozilla Firefox 88.0.1, 88.1.3. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1701684
• https://www.mozilla.org/security/advisories/mfsa2021-20/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1701684
• https://www.mozilla.org/security/advisories/mfsa2021-20/

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