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Fencer Vulns
medium 6.5

CVE-2022-29916 json

Firefox behaved slightly differently for already known resources when loading CSS resources involving CSS variables.

published 2022-12-22 3 y ago modified 2026-06-17 4 mo ago also EUVD-2022-34226

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

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.

Patch / fix

  • Mozilla Thunderbird 91.9
  • Mozilla Firefox ESR 91.9
  • Mozilla Firefox 100
  • firefox-esr Debian 14, Debian 13, Debian 12 91.9.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:91.9.0-1

debian advisories DEBIAN-CVE-2022-29916

  • firefox Ubuntu 18.04 LTS 100.0+build2-0ubuntu0.18.04.1
  • firefox Ubuntu 20.04 LTS 100.0+build2-0ubuntu0.20.04.1
  • thunderbird Ubuntu 18.04 LTS 1:91.9.1+build1-0ubuntu0.18.04.1
  • thunderbird Ubuntu 20.04 LTS 1:91.9.1+build1-0ubuntu0.20.04.1
  • thunderbird Ubuntu 22.04 LTS 1:91.9.1+build1-0ubuntu0.22.04.1

ubuntu advisories UBUNTU-CVE-2022-29916

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 9 91.9.0-3.el9_0
  • thunderbird RHEL 7 91.9.0-3.el7_9
  • thunderbird RHEL 8 91.9.0-3.el8_5
  • firefox RHEL 7 91.9.0-1.el7_9
  • firefox RHEL 8 91.9.0-1.el8_5
  • firefox RHEL 9 91.9.0-1.el9_0
  • thunderbird RHEL 8.4 EUS 91.9.0-3.el8_4
  • thunderbird RHEL 8.2 EUS 91.9.0-3.el8_2

red hat advisories RHSA-2022:4589RHSA-2022:1726RHSA-2022:1725RHSA-2022:1724RHSA-2022:1727RHSA-2022:1730

  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 91.9.0-112.108.4
  • MozillaFirefox SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +10 more 91.9.0-150200.152.37.3
  • MozillaFirefox SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +7 more 91.9.0-150000.150.38.3
  • MozillaThunderbird SLE Workstation Extension 15 SP4, SLE Workstation Extension 15 SP3, SLE Module for Package Hub 15 SP4 +3 more 91.9.0-150200.8.68.2
  • MozillaFirefox SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +10 more 91.9.0-150200.152.33.1

suse advisories SUSE-SU-2022:1757-1SUSE-SU-2022:1748-1SUSE-SU-2022:1731-1SUSE-SU-2022:1719-1SUSE-RU-2022:1579-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 100.0-1.1
  • MozillaThunderbird openSUSE Tumbleweed 91.9.0-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:12044-1openSUSE-SU-2024:12045-1

  • thunderbird AlmaLinux 8 91.9.0-3.el8_5.alma
  • firefox AlmaLinux 8 91.9.0-1.el8_5.alma

almalinux advisories ALSA-2022:1730ALSA-2022:1705

  • thunderbird Rocky Linux 8 91.9.0-3.el8_5
  • firefox Rocky Linux 8 91.9.0-1.el8_5

rocky linux advisories RLSA-2022:1730RLSA-2022:1705

  • firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 100.0-r0
  • librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 100.0-r0
  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +6 more 91.9.0-r0
  • thunderbird Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 91.9.0-r0

alpine advisories ALPINE-CVE-2022-29916

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 100.0-1
  • thunderbird Arch Linux 91.9-1

arch linux advisories AVG-2709AVG-2710

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-2022-29916 updated cvss 7.5

Mozilla: Leaking browser history with CSS variables

  • Red Hat Enterprise Linux 6 firefox, thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 91.9.0-1.el8_5, thunderbird 91.9.0-3.el8_5
    fixed: vendor fix RHSA-2022:1705
  • Red Hat Enterprise Linux AppStream (v. 9) firefox 91.9.0-1.el9_0, thunderbird 91.9.0-3.el9_0
    fixed: vendor fix RHSA-2022:4590
  • Red Hat Enterprise Linux AppStream E4S (v. 8.1) firefox 91.9.0-1.el8_1, thunderbird 91.9.0-3.el8_1
    fixed: vendor fix RHSA-2022:1701
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox 91.9.0-1.el8_2, thunderbird 91.9.0-3.el8_2
    fixed: vendor fix RHSA-2022:1704
  • Red Hat Enterprise Linux AppStream EUS (v.8.4) firefox 91.9.0-1.el8_4, thunderbird 91.9.0-3.el8_4
    fixed: vendor fix RHSA-2022:1702
  • Red Hat Enterprise Linux Client (v. 7) firefox 91.9.0-1.el7_9, thunderbird 91.9.0-3.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) firefox 91.9.0-1.el7_9 Red Hat Enterprise Linux Server (v. 7) firefox 91.9.0-1.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) firefox 91.9.0-1.el7_9, thunderbird 91.9.0-3.el7_9 Red Hat Enterprise Linux Workstation (v. 7) firefox 91.9.0-1.el7_9, thunderbird 91.9.0-3.el7_9 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 91.9.0-1.el7_9
    fixed: vendor fix RHSA-2022:1703

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

0.76% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2022-16/ referenced PoC, tagged "exploit" by a source, unverified
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2022-18/ referenced PoC, tagged "exploit" by a source, unverified
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2022-17/ referenced PoC, tagged "exploit" by a source, unverified
  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1760674 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected products

  • Mozilla Thunderbird
  • Mozilla Firefox ESR
  • Mozilla Firefox

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

Sources

Fencer Vulns 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.