What’s Vulnerable › Vulnerabilities

CVE-2022-29916

• Severity: medium (CVSS 6.5 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: yes
• Published: 2022-12-22 · updated 2026-06-17
• Weakness: CWE-200

Description

Firefox behaved slightly differently for already known resources when loading CSS resources involving CSS variables. This could have been used to probe the browser history. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.

Affected products

• Mozilla Firefox: before 100.0 — fixed in 100.0
• Mozilla Firefox ESR: before 91.9 — fixed in 91.9
• Mozilla Thunderbird: before 91.9 — fixed in 91.9

How to fix

Upgrade to a fixed version: Mozilla Firefox 100.0; Mozilla Firefox ESR 91.9; Mozilla Thunderbird 91.9. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1760674
• https://www.mozilla.org/security/advisories/mfsa2022-16/
• https://www.mozilla.org/security/advisories/mfsa2022-17/
• https://www.mozilla.org/security/advisories/mfsa2022-18/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1760674
• https://www.mozilla.org/security/advisories/mfsa2022-16/
• https://www.mozilla.org/security/advisories/mfsa2022-17/
• https://www.mozilla.org/security/advisories/mfsa2022-18/

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