CVE-2021-4140: mozilla firefox
CVSS: 10.0v3.1CriticalModified
AliasesUBUNTU-CVE-2021-4140DEBIAN-CVE-2021-4140
Published 22-12-2022Last modified 16-04-2025
Vulnerability summary
CVE-2021-4140 is a critical (CVSS 10.0) vulnerability in mozilla firefox. EPSS estimates a 1.35% chance of exploitation in the next 30 days, higher than 71.1% of scored vulnerabilities. 1 public exploit is recorded.
CVSS score
10.0/10
010
Critical · v3.1 (NVD)EPSS score
1.35%
0%100%
Low · +0.01 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference
Advisory lineage
Upstream 0 · Downstream 28 · Related 12DLA-2880-1DLA-2881-1DSA-5044-1DSA-5045-1MGASA-2022-0013MGASA-2022-0019OPENSUSE-SU-2022:0136-1OPENSUSE-SU-2022:0199-1OPENSUSE-SU-2024:11732-1OPENSUSE-SU-2024:11733-1OPENSUSE-SU-2024:14572-1RHSA-2022:0123RHSA-2022:0124RHSA-2022:0125RHSA-2022:0126RHSA-2022:0127RHSA-2022:0128RHSA-2022:0129RHSA-2022:0130RHSA-2022:0131RHSA-2022:0132SUSE-SU-2022:0115-1SUSE-SU-2022:0136-1SUSE-SU-2022:0137-1SUSE-SU-2022:0199-1SUSE-SU-2022:14880-1USN-5229-1USN-5248-1
Timeline
- 22-12-2022PublishedVulnerability first disclosed.
- 16-04-2025Last modifiedVulnerability information updated.
Description
It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.
CVSS metrics
4 scores · 4 sources · 1 versionCritical 10.0Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HSources4 sources · 9.8–10.0
- CVE.orgCNA9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HDiffers
- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HDiffers
- OSV · DebianEcosystem advisory · calculated10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS trend
Probability
1.35%
Chance of exploitation in the next 30 days
Percentile
71%
Versus all other CVEs
30-day change
+0.01 pp
From 1.34% on 19-09-2026
19-09-202619-10-2026
EPSS score1.35%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 foundExploit Reference (bugzilla.mozilla.org)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Ubuntu6 products
- firefox< 96.0+build2-0ubuntu0.18.04.1 | < 96.0+build2-0ubuntu0.20.04.1 | < 96.0+build2-0ubuntu1
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
- mozjs78All versions (No fix recorded)
Mozilla3 products
- firefox≥ unspecified, < 96 | < 96.0
- firefox_esr≥ unspecified, < 91.5 | < 91.5
- thunderbird≥ unspecified, < 91.5 | < 91.5
Debian2 products
- firefox-esr< 91.5.0esr-1
- thunderbird< 1:91.5.0-1
3 vendors · 11 products
References
13 links- www.mozilla.org/security/advisories/mfsa2022-01/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2022-02/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2022-03/Vendor Advisory
