CVE-2021-23968

Name: CVE-2021-23968
Creator: NVD / NIST
Published: 2021-02-26T02:15:12.82+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 1.22%

Last modified Jun 17, 2026

CVE-2021-23968 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. If Content Security Policy blocked frame navigation, the full destination of a redirect served in the frame was reported in the violation report; as opposed to the original frame URI. This could be used to leak sensitive information contained in such URIs. EPSS estimates a 1.22% chance of exploitation in the next 30 days.

Description

If Content Security Policy blocked frame navigation, the full destination of a redirect served in the frame was reported in the violation report; as opposed to the original frame URI. This could be used to leak sensitive information contained in such URIs. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.

Metrics

CVSS 3.1

4.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

EPSS Probability

1.22%

64.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-209

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 86.0
Mozilla	Firefox Esr	< 78.8
Mozilla	Thunderbird	< 78.8
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1687342Issue Tracking, Permissions Required, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00000.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202104-09Third Party Advisory
https://security.gentoo.org/glsa/202104-10Third Party Advisory
https://www.debian.org/security/2021/dsa-4866Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2021-07/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-08/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-09/Release Notes, Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1687342Issue Tracking, Permissions Required, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00000.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202104-09Third Party Advisory
https://security.gentoo.org/glsa/202104-10Third Party Advisory
https://www.debian.org/security/2021/dsa-4866Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2021-07/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-08/Release Notes, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-09/Release Notes, Vendor Advisory

Timeline

Published: Feb 26, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-23968?

How severe is CVE-2021-23968?

CVE-2021-23968 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 1.22% probability of exploitation in the next 30 days.

How do I fix CVE-2021-23968?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-23968?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST