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Fencer Intel
medium 4.3

CVE-2021-23968 json

If Content Security Policy blocked frame navigation, the full destination of a redirect served in the frame was reported in the violation r…

published 5y ago modified 4mo ago also EUVD-2021-10889

cvss
4.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

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.

Patch / fix

  • mozilla firefox 86.0
  • mozilla firefox_esr 78.8
  • mozilla thunderbird 78.8
  • firefox-esr Debian 14, Debian 13, Debian 12 78.8.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:78.8.0-1

debian advisories DEBIAN-CVE-2021-23968

  • firefox Ubuntu 16.04 LTS 86.0+build3-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 86.0+build3-0ubuntu0.18.04.1
  • firefox Ubuntu 20.04 LTS 86.0+build3-0ubuntu0.20.04.1
  • thunderbird Ubuntu 18.04 LTS 1:78.8.1+build1-0ubuntu0.18.04.1
  • thunderbird Ubuntu 20.04 LTS 1:78.8.1+build1-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2021-23968

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • thunderbird RHEL 7 78.8.0-1.el7_9
  • thunderbird RHEL 8 78.8.0-1.el8_3
  • firefox RHEL 7 78.8.0-1.el7_9
  • firefox RHEL 8 78.8.0-1.el8_3
  • thunderbird RHEL 8.1 EUS 78.8.0-1.el8_1
  • thunderbird RHEL 8.2 EUS 78.8.0-1.el8_2
  • firefox RHEL 8.1 EUS 78.8.0-1.el8_1
  • firefox RHEL 8.2 EUS 78.8.0-1.el8_2

red hat advisories RHSA-2021:0661RHSA-2021:0658RHSA-2021:0662RHSA-2021:0657RHSA-2021:0656RHSA-2021:0659

  • MozillaFirefox SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 78.8.0-3.133.1
  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +14 more 78.8.0-112.51.1
  • MozillaThunderbird SLE Workstation Extension 15 SP2 78.8.0-8.15.4
  • MozillaFirefox SLE Module for Desktop Applications 15 SP2 78.8.0-8.32.2
  • MozillaFirefox SLES 11 SP4-LTSS 78.8.0-78.120.1

suse advisories SUSE-SU-2021:0676-1SUSE-SU-2021:0667-1SUSE-SU-2021:14657-1SUSE-SU-2021:0661-1SUSE-SU-2021:0659-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1
  • MozillaThunderbird openSUSE Leap 15.2 78.8.0-lp152.2.35.1
  • MozillaFirefox openSUSE Leap 15.2 78.8.0-lp152.2.49.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2024:10601-1openSUSE-SU-2021:0387-1openSUSE-SU-2021:0373-1

  • firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +8 more 87.0-r0
  • librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 87.0-r0
  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 78.8.0-r0
  • thunderbird Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 78.9.0-r0

alpine advisories ALPINE-CVE-2021-23968

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • firefox Arch Linux 86.0-1
  • thunderbird Arch Linux 78.8.0-1

arch linux advisories AVG-1599AVG-1601

Is CVE-2021-23968 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-23968 updated cvss 4.3

Mozilla: Content Security Policy violation report could have contained the destination of a redirect

  • Red Hat Enterprise Linux 6 firefox, thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 78.8.0-1.el8_3, thunderbird 78.8.0-1.el8_3
    fixed: vendor fix RHSA-2021:0655
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox 78.8.0-1.el8_1, thunderbird 78.8.0-1.el8_1
    fixed: vendor fix RHSA-2021:0659
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox 78.8.0-1.el8_2, thunderbird 78.8.0-1.el8_2
    fixed: vendor fix RHSA-2021:0660
  • Red Hat Enterprise Linux Client (v. 7) firefox 78.8.0-1.el7_9, thunderbird 78.8.0-1.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) firefox 78.8.0-1.el7_9 Red Hat Enterprise Linux Server (v. 7) firefox 78.8.0-1.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) firefox 78.8.0-1.el7_9, thunderbird 78.8.0-1.el7_9 Red Hat Enterprise Linux Workstation (v. 7) firefox 78.8.0-1.el7_9, thunderbird 78.8.0-1.el7_9 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 78.8.0-1.el7_9
    fixed: vendor fix RHSA-2021:0656

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.31% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Affected products

  • Mozilla Firefox
  • Mozilla Thunderbird
  • Mozilla Firefox ESR

Classification

Weakness
  • CWE-209 Generation of Error Message Containing Sensitive Information

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.