CVE-2026-4729
published 2026-03-24CVE-2026-4729: Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort…
PriorityP348critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.33%
25.5th percentile
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. 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
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
osv9.8CRITICAL
vendor_debian9.8CRITICAL
vendor_redhat9.8CRITICAL
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Red Hat
firefox: Memory safety bugs fixed in Firefox 149 and Thunderbird 149
vendor_redhat·2026-03-24·CVSS 9.8
CVE-2026-4729 [CRITICAL] CWE-825 firefox: Memory safety bugs fixed in Firefox 149 and Thunderbird 149
firefox: Memory safety bugs fixed in Firefox 149 and Thunderbird 149
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149 and Thunderbird < 149.
A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Ad
Debian
CVE-2026-4729: firefox - Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bug...
vendor_debian·2026·CVSS 9.8
CVE-2026-4729 [CRITICAL] CVE-2026-4729: firefox - Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bug...
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. 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-2026-4729
vendor_mozilla·CVSS 9.8
CVE-2026-4729 [CRITICAL] Mozilla Foundation Security Advisory 2026-20: CVE-2026-4729
Mozilla Foundation Security Advisory 2026-20
CVE: CVE-2026-4729
Product: Firefox
Impact: high
Fixed in: Firefox 149
Mozilla
Mozilla Foundation Security Advisory 2026-23: CVE-2026-4729
vendor_mozilla·CVSS 9.8
CVE-2026-4729 [CRITICAL] Mozilla Foundation Security Advisory 2026-23: CVE-2026-4729
Mozilla Foundation Security Advisory 2026-23
CVE: CVE-2026-4729
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 149
VulDB
Mozilla Firefox up to 148 memory corruption (Nessus ID 304138)
vuldb·2026-07-01·CVSS 9.8
CVE-2026-4729 [CRITICAL] Mozilla Firefox up to 148 memory corruption (Nessus ID 304138)
A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 148. Affected by this vulnerability is an unknown functionality. This manipulation causes memory corruption.
The identification of this vulnerability is CVE-2026-4729. It is possible to initiate the attack remotely. There is no exploit available.
It is advisable to upgrade the affected component.
OSV
CVE-2026-4729: Memory safety bugs present in Firefox 148 and Thunderbird 148
osv·2026-03-24·CVSS 9.8
CVE-2026-4729 [CRITICAL] CVE-2026-4729: Memory safety bugs present in Firefox 148 and Thunderbird 148
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149 and Thunderbird < 149.
GHSA
GHSA-xh4v-qr89-3hj3: Memory safety bugs present in Firefox 148 and Thunderbird 148
ghsa_unreviewed·2026-03-24
CVE-2026-4729 [CRITICAL] CWE-120 GHSA-xh4v-qr89-3hj3: Memory safety bugs present in Firefox 148 and Thunderbird 148
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-4729 firefox: Memory safety bugs fixed in Firefox 149 and Thunderbird 149
bugzilla·2026-03-24·CVSS 9.8
CVE-2026-4729 [CRITICAL] CVE-2026-4729 firefox: Memory safety bugs fixed in Firefox 149 and Thunderbird 149
CVE-2026-4729 firefox: Memory safety bugs fixed in Firefox 149 and Thunderbird 149
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149.
Wiz
CVE-2026-4729 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 5.1
CVE-2026-4729 [MEDIUM] CVE-2026-4729 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-4729 :
NixOS vulnerability analysis and mitigation
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149 and Thunderbird < 149.
Source : NVD
## 9.8
Score
Published March 24, 2026
Severity CRITICAL
CNA Score 9.8
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) 5.3
Exploitation Probability (EPSS) N/A
Affected packages and libraries
thunderbird
firefox
Sources
Chainguard Has Fix Added at: Mar 29, 2026
Homebrew Severity CRI
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1944033%2C1997282%2C2009213%2C2011412%2C2021925%2C2022034https://www.mozilla.org/security/advisories/mfsa2026-20/https://www.mozilla.org/security/advisories/mfsa2026-23/https://access.redhat.com/security/cve/CVE-2026-4729https://bugzilla.redhat.com/show_bug.cgi?id=2450745https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4729.json
2026-03-24
Published