What is CVE-2022-26485?

CVE-2022-26485 is a high-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 8.8/10. Published 2022-12-22.

How severe is CVE-2022-26485?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2022-26485 known to be exploited?

Yes. CVE-2022-26485 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-07), indicating it is being actively exploited. 9 public proof-of-concept repositories are indexed.

Use After Free in Mozilla Firefox

CVE-2022-26485

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.

Vulnerability class: Use-After-Free

Published 2022-12-22 · last modified 2026-08-19.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.143 (96.6th percentile), scored 2026-10-19.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 97th percentile — 96.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.143 · newest: 0.143 · change: 0.000

Affected products

Mozilla Firefox — versions unspecified
Mozilla Firefox Esr — versions unspecified
Mozilla Firefox Focus
Mozilla Firefox For Android — versions unspecified
Mozilla Firefox Mobile
Mozilla Focus — versions unspecified
Mozilla Thunderbird — versions unspecified

Weakness classification (CWE)

CWE-416 — Use After Free

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-03-07. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-03-21.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

www.mozilla.org/security/advisories/mfsa2022-09/ (Vendor Advisory)
bugzilla.mozilla.org/show_bug.cgi (Exploit, Issue Tracking, Vendor Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2022-26485?: CVE-2022-26485 is a high-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 8.8/10. Published 2022-12-22.
How severe is CVE-2022-26485?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2022-26485 known to be exploited?: Yes. CVE-2022-26485 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-07), indicating it is being actively exploited. 9 public proof-of-concept repositories are indexed.