Vulnerability in Mozilla Firefox
CVE-2021-23969
As specified in the W3C Content Security Policy draft, when creating a violation report, "User agents need to ensure that the source file is the URL requested by the page, pre-redirects. If that’s not possible, user agents need to strip the URL down to an origin to avoid unintentional leakage." Under certain types of redirects, Firefox incorrectly set the source file to be the destination of the redirects. This was fixed to be the redirect destination's origin. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.
EPSS: 0.012 (65.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N.
Affected products
- Mozilla Firefox — versions < 86
- Mozilla Firefox Esr — versions < 78.8
- Mozilla Firefox_esr
- Mozilla Thunderbird — versions < 78.8
- Debian Debian_linux — versions 9.0, 10.0
References
- security@mozilla.org (x_refsource_MISC, Release Notes, Vendor Advisory)
- security@mozilla.org (x_refsource_MISC, Release Notes, Vendor Advisory)
- security@mozilla.org (x_refsource_MISC, Release Notes, Vendor Advisory)
- security@mozilla.org (Permissions Required, x_refsource_MISC, Issue Tracking, Vendor Advisory)
- security@mozilla.org (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory)
- security@mozilla.org (vendor-advisory, Third Party Advisory, x_refsource_DEBIAN)
- security@mozilla.org (vendor-advisory, Third Party Advisory, x_refsource_GENTOO)
- security@mozilla.org (vendor-advisory, Third Party Advisory, x_refsource_GENTOO)
Frequently asked questions
- What is CVE-2021-23969?
- CVE-2021-23969 is a medium-severity vulnerability in Mozilla Firefox. CVSS score: 4.3/10. Published 2021-02-26.
- How severe is CVE-2021-23969?
- Medium severity. CVSS v3 base score is 4.3 out of 10.