CVE-2026-5734Critical
DEB
DEB
Debian Security Advisories (DSA)
DSAs are published by the Debian Security Team for issues affecting the stable distribution. The downstream tracker (security-tracker.debian.org) additionally maps every CVE to its package-level status across all supported suites.
Region
Intl.
Updates
1 ч
License
Public Domain
Advisories covering the Debian stable and oldstable releases. Ship notes include the exact .deb version that remediates each issue.
https://www.debian.org/security/ →Share link
Anyone with the link can open this vulnerability.
Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs sho…
CVSS
9.8
Critical
EPSS
0.00
p23
Published
2026-01-01
Updated
2026-01-01
Description
Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.
Tags · CWE
RCEPre-auth
CWE-787
CWE-787BaseDraft
Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
https://cwe.mitre.org/data/definitions/787.html →Open in CWE collection →Affected products
Firefox < 140.9.1Firefox < 149.0.2Thunderbird < 140.9.1Thunderbird < 149.0.2
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Timeline
2026-01-01
Published
2026-01-01
Updated
CVSS 3.1 breakdown
Attack Vector
AV: N
Network (N)
Attack Complexity
AC: L
Low (L)
Privileges Required
PR: N
None (N)
User Interaction
UI: N
None (N)
Scope
S: U
Unchanged (U)
Confidentiality Impact
C: H
High (H)
Integrity Impact
I: H
High (H)
Availability Impact
A: H
High (H)
Exploit indicators
EPSS
0.003 · p23
Known exploited (KEV)
No
Known exploits — Сканер-ВС
No Сканер-ВС checks registered for this vulnerability yet.
Affected products
| Product | Vendor | Status |
|---|---|---|
| firefox | Tracked | |
| firefox-esr | Tracked | |
| thunderbird | Tracked | |
| firefox | * | Tracked |
| thunderbird | * | Tracked |
Source databases
DEB
DEB
Debian Security Advisories (DSA)
DSAs are published by the Debian Security Team for issues affecting the stable distribution. The downstream tracker (security-tracker.debian.org) additionally maps every CVE to its package-level status across all supported suites.
Region
Intl.
Updates
1 ч
License
Public Domain
Advisories covering the Debian stable and oldstable releases. Ship notes include the exact .deb version that remediates each issue.
https://www.debian.org/security/ →CVE
CVE
National Vulnerability Database
NVD is the U.S. government repository of standards-based vulnerability management data, built on top of the MITRE CVE list. Every record includes CPE applicability statements, CVSS v2 and v3.x base scores, CWE mappings and cross-references to advisories.
Region
US
Updates
15 min
License
Public Domain
Comprehensive catalog of publicly disclosed vulnerabilities with CPE matches, CVSS scoring and reference URLs. De-facto standard for cross-vendor correlation.
https://nvd.nist.gov →Related vulnerabilities