What is CVE-2022-34476?

CVE-2022-34476 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Input Validation. CVSS score: 9.8/10. Published 2022-12-22.

How severe is CVE-2022-34476?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Improper input validation in Mozilla Firefox

CVE-2022-34476

ASN.1 parsing of an indefinite SEQUENCE inside an indefinite GROUP could have resulted in the parser accepting malformed ASN.1. This vulnerability affects Firefox < 102.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2022-12-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (51.2th percentile), scored 2026-10-04.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: -0.000

Affected products

Mozilla Firefox — versions unspecified

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

www.mozilla.org/security/advisories/mfsa2022-24/ (Vendor Advisory)
bugzilla.mozilla.org/show_bug.cgi (Permissions Required, Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2022-34476?: CVE-2022-34476 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Input Validation. CVSS score: 9.8/10. Published 2022-12-22.
How severe is CVE-2022-34476?: Critical severity. CVSS v3 base score is 9.8 out of 10.