What’s Vulnerable › Vulnerabilities

CVE-2021-23976

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-02-26 · updated 2026-06-17
• Weakness: CWE-1021

Description

When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and allowed declaring webapp manifests for other origins. This could be used to gain fullscreen access for UI spoofing and could also lead to cross-origin attacks on targeted websites. Note: This issue is a different issue from CVE-2020-26954 and only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 86.

Affected products

• Mozilla Firefox: before 86.0 — fixed in 86.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 86.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1684627
• https://security.gentoo.org/glsa/202104-10
• https://www.mozilla.org/security/advisories/mfsa2021-07/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1684627
• https://security.gentoo.org/glsa/202104-10
• https://www.mozilla.org/security/advisories/mfsa2021-07/

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