CVE-2022-26485: Mozilla Firefox Use-After-Free Vulnerability

Q: How do I fix CVE-2022-26485?

firefox: upgrade to 91.6.1, 97.0.2; firefox focus: upgrade to 97.3.0; firefox mobile: upgrade to 97.3.0. Exact commands for each OS are on this page.

Q: Is CVE-2022-26485 being exploited?

Yes. CVE-2022-26485 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2022-26485 affect?

CVE-2022-26485 affects firefox, firefox focus, firefox mobile. Severity is high (CVSS 8.8). Removing an XSLT parameter during processing could have lead to an exploitable use-after-free. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Andr

Q: How urgent is CVE-2022-26485?

Priority 85/100. High severity; EPSS top 3%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference

Patch now

HIGH 8.8EXPLOITEDUPGRADEUPGRADEUPGRADE

CVE-2022-26485 is a high-severity flaw (CVSS 8.8) affecting firefox, firefox focus, firefox mobile, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Removing an XSLT parameter during processing could have lead to an exploitable use-after-free. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Android < 97.3.0, Thunderbird < 91.6.2, and Focus < 97.3.0.

Why this priority

High severity
EPSS top 3%: very likely to be exploited
Exploited in the wild (CISA KEV)
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	14.3% (top 3%)
CISA exploited list	Yes, fix due 2022-03-21
Weakness	CWE-416
Published	2022-12-22
Last modified	2026-08-19

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

Last updated 2026-08-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-03-07Exploited Added to the CISA Known Exploited Vulnerabilities list
2022-03-21Deadline CISA due date for US federal agencies to patch
2022-12-22 20:15 UTCPublished CVE record published
2026-08-19 15:29 UTCUpdated Record last modified

mozilla firefox UPGRADE

Affected: < 91.6.1 · < 97.0.2

Fixed in: 91.6.1, 97.0.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy firefox || rpm -q firefox || firefox --version

2. UPGRADE to 91.6.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade firefox

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firefox

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

mozilla firefox focus UPGRADE

Affected: < 97.3.0

Fixed in: 97.3.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy firefox-focus || rpm -q firefox-focus || firefox-focus --version

2. UPGRADE to 97.3.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade firefox-focus

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firefox-focus

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

mozilla firefox mobile UPGRADE

Affected: < 97.3.0

Fixed in: 97.3.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy firefox-mobile || rpm -q firefox-mobile || firefox-mobile --version

2. UPGRADE to 97.3.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade firefox-mobile

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firefox-mobile

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

mozilla thunderbird UPGRADE

Affected: < 91.6.2

Fixed in: 91.6.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy thunderbird || rpm -q thunderbird || thunderbird --version

2. UPGRADE to 91.6.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade thunderbird

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade thunderbird

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Fedora ELN · libslirp · FIXED · 4.9.7-1.eln159 · FEDORA-2026-209cb94e13 · source

sudo dnf upgrade --advisory=FEDORA-2026-209cb94e13

Fedora 46 · modpoll · FIXED · 1.6.1-1.fc46 · FEDORA-2026-60d403ff15 · source

sudo dnf upgrade --advisory=FEDORA-2026-60d403ff15

Ubuntu 20.04 · firefox · FIXED · 97.0.2+build1-0ubuntu0.20.04.1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "97.0.2+build1-0ubuntu0.20.04.1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · firefox · FIXED · 1:1snap1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "1:1snap1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · firefox-esr · FIXED · 91.6.1esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "91.6.1esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · firefox-esr · FIXED · 91.6.1esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "91.6.1esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · thunderbird · FIXED · 1:91.6.2-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:91.6.2-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · thunderbird · FIXED · 1:91.6.2-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:91.6.2-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 7 · firefox · FIXED · firefox-91.7.0-3.el7_9

sudo dnf upgrade --advisory=RHSA-2022:0824 rpm -q firefox

RHEL 7 · thunderbird · FIXED · thunderbird-91.7.0-2.el7_9

sudo dnf upgrade --advisory=RHSA-2022:0850 rpm -q thunderbird

RHEL 8 · firefox · FIXED · firefox-91.7.0-3.el8_5

sudo dnf upgrade --advisory=RHSA-2022:0818 rpm -q firefox

RHEL 8 · thunderbird · FIXED · thunderbird-91.7.0-2.el8_5

sudo dnf upgrade --advisory=RHSA-2022:0845 rpm -q thunderbird

RHEL 8.1 Update Services for SAP Solutions · firefox · FIXED · firefox-91.7.0-3.el8_1

sudo dnf upgrade --advisory=RHSA-2022:0815 rpm -q firefox

Alpine 3.20 · firefox-esr · FIXED · firefox-esr-91.6.1-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Alpine 3.20 · firefox · FIXED · firefox-97.0.2-r0

apk add --upgrade firefox apk info -v firefox

Alpine 3.20 · thunderbird · FIXED · thunderbird-91.6.2-r0

apk add --upgrade thunderbird apk info -v thunderbird

Alpine 3.21 · firefox-esr · FIXED · firefox-esr-91.6.1-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Amazon Linux 2 · see advisory · FIXED · ALAS2-2022-1779 · source

sudo yum update --advisory=ALAS2-2022-1779

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: mistymntncop/CVE-2022-26485 (17 stars)

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2022-26485?

firefox: upgrade to 91.6.1, 97.0.2; firefox focus: upgrade to 97.3.0; firefox mobile: upgrade to 97.3.0. Exact commands for each OS are on this page.

Is CVE-2022-26485 being exploited?

Yes. CVE-2022-26485 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2022-26485 affect?

CVE-2022-26485 affects firefox, firefox focus, firefox mobile. Severity is high (CVSS 8.8). Removing an XSLT parameter during processing could have lead to an exploitable use-after-free. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Andr

How urgent is CVE-2022-26485?

Priority 85/100. High severity; EPSS top 3%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference

Software pages

Android vulnerabilities · Mozilla Firefox vulnerabilities · Mozilla Thunderbird vulnerabilities

Related CVEs

CVE-2026-74990 CRITICAL 9.8 UPGRADE UPGRADE Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153
CVE-2026-74989 CRITICAL 9.8 UPGRADE UPGRADE Internally found bugs present in Firefox 153
CVE-2026-74988 CRITICAL 9.8 UPGRADE UPGRADE Internally found bugs present in Firefox ESR 153.0 and Firefox 153
CVE-2026-74987 CRITICAL 9.8 UPGRADE UPGRADE Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153
CVE-2026-74969 HIGH 8.8 UPGRADE UPGRADE Race condition, use-after-free in the Layout: Text and Fonts component

References

← Back to latest CVEs