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

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 7 Mar 2022, 290 days before the CVE record was published.

How likely is exploitation in the next 30 days?

14.3%

EPSS score, percentile 96.6 of all scored records

How severe?

8.8 High

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 21 Mar 2022. Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

• before 97.0.2
• before 91.6.1
• before 97.3.0
• before 91.6.2
• before 97.3.0

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 21 March 2022.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

• https://nvd.nist.gov/vuln/detail/CVE-2022-26485

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Mozilla Firefox contains a use-after-free vulnerability in XSLT parameter processing which can be exploited to perform arbitrary code execution.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2022-26485 to its Known Exploited Vulnerabilities (KEV) catalog on 7 Mar 2022.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 21 Mar 2022.
• The CVE record was published on 22 Dec 2022, 290 days after it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 8.8 (High), taken from CISA's enrichment of the record.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 14.3% (percentile 96.6), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

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.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-416: Use After Free

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• mozilla.org
• bugzilla.mozilla.org

More exploited Mozilla vulnerabilities

• CVE-2010-3765: Mozilla Multiple Products Remote Code Execution Vulnerability (added 6 Oct 2025)
• CVE-2024-9680: Mozilla Firefox Use-After-Free Vulnerability (added 15 Oct 2024)
• CVE-2016-9079: Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Vulnerability (added 22 Jun 2023)
• CVE-2015-4495: Mozilla Firefox Security Feature Bypass Vulnerability (added 25 May 2022)
• CVE-2019-11707: Mozilla Firefox and Thunderbird Type Confusion Vulnerability (added 23 May 2022)
• CVE-2019-11708: Mozilla Firefox and Thunderbird Sandbox Escape Vulnerability (added 23 May 2022)