CVE-2026-4726
published 2026-03-24CVE-2026-4726: Denial-of-service in the XML component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.
PriorityP339high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.53%
41.7th percentile
Denial-of-service in the XML component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.
Affected
4 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | firefox | < firefox 149.0-1 (sid) | firefox 149.0-1 (sid) |
| mozilla | firefox | < 149.0 | 149.0 |
| mozilla | firefox | — | — |
| mozilla | thunderbird | < 149.0 | 149.0 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
osv7.5HIGH
vendor_debian7.5HIGH
vendor_redhat7.5HIGH
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GHSA
GHSA-2r77-x4qh-mhc3: Denial-of-service in the XML component
ghsa_unreviewed·2026-03-24
CVE-2026-4726 [HIGH] CWE-400 GHSA-2r77-x4qh-mhc3: Denial-of-service in the XML component
Denial-of-service in the XML component. This vulnerability affects Firefox < 149.
OSV
CVE-2026-4726: Denial-of-service in the XML component
osv·2026-03-24·CVSS 7.5
CVE-2026-4726 [HIGH] CVE-2026-4726: Denial-of-service in the XML component
Denial-of-service in the XML component. This vulnerability affects Firefox < 149 and Thunderbird < 149.
Red Hat
firefox: Denial-of-service in the XML component
vendor_redhat·2026-03-24·CVSS 7.5
CVE-2026-4726 [HIGH] CWE-776 firefox: Denial-of-service in the XML component
firefox: Denial-of-service in the XML component
Denial-of-service in the XML component. This vulnerability affects Firefox < 149 and Thunderbird < 149.
A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
Denial-of-service in the XML component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: firefox (Red Hat Enterprise Linux 10) - Not affected
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Not affected
Package: firefox (Red Hat Enterprise Linux 6) - Not affected
Package: firefox (Red Hat Enterprise Linux 7) - Not affected
Package: firefox (Red Hat Enterprise Linux 8) - Not affected
Package: firefox (Red Hat Enterprise Linux 9) -
Debian
CVE-2026-4726: firefox - Denial-of-service in the XML component. This vulnerability affects Firefox < 149...
vendor_debian·2026·CVSS 7.5
CVE-2026-4726 [HIGH] CVE-2026-4726: firefox - Denial-of-service in the XML component. This vulnerability affects Firefox < 149...
Denial-of-service in the XML component. This vulnerability affects Firefox < 149 and Thunderbird < 149.
Scope: local
sid: resolved (fixed in 149.0-1)
Mozilla
Mozilla Foundation Security Advisory 2026-20: CVE-2026-4726
vendor_mozilla·CVSS 7.5
CVE-2026-4726 [HIGH] Mozilla Foundation Security Advisory 2026-20: CVE-2026-4726
Mozilla Foundation Security Advisory 2026-20
CVE: CVE-2026-4726
Product: Firefox
Impact: high
Fixed in: Firefox 149
Mozilla
Mozilla Foundation Security Advisory 2026-23: CVE-2026-4726
vendor_mozilla·CVSS 7.5
CVE-2026-4726 [HIGH] Mozilla Foundation Security Advisory 2026-23: CVE-2026-4726
Mozilla Foundation Security Advisory 2026-23
CVE: CVE-2026-4726
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 149
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-4726 firefox: Denial-of-service in the XML component
bugzilla·2026-03-24·CVSS 7.5
CVE-2026-4726 [HIGH] CVE-2026-4726 firefox: Denial-of-service in the XML component
CVE-2026-4726 firefox: Denial-of-service in the XML component
Denial-of-service in the XML component. This vulnerability affects Firefox < 149.
Wiz
CVE-2026-4726 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 5.1
CVE-2026-4726 [MEDIUM] CVE-2026-4726 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-4726 :
NixOS vulnerability analysis and mitigation
Denial-of-service in the XML component. This vulnerability affects Firefox < 149 and Thunderbird < 149.
Source : NVD
## 7.5
Score
Published March 24, 2026
Severity HIGH
CNA Score 7.5
Affected Technologies
NixOS
Mozilla Firefox
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 4
Exploitation Probability (EPSS) N/A
Affected packages and libraries
cpe:2.3:a:mozilla:firefox
cpe:2.3:a:mozilla:thunderbird
Sources
Chainguard Has Fix Added at: Mar 29, 2026
Homebrew Severity HIGH Has Fix Added at: Mar 29, 2026
Nix Severity HIGH Has Fix Added at: Mar 29, 2026
Ubuntu 22.04 Severity MEDIUM No Fix Added at: Mar 29, 2026
Linux S
2026-03-24
Published