CVE-2026-2771
published 2026-02-24CVE-2026-2771: Undefined behavior in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and…
PriorityP348critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.48%
39.8th percentile
Undefined behavior in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Affected
13 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | firefox | < firefox 148.0-1 (sid) | firefox 148.0-1 (sid) |
| debian | firefox-esr | < firefox 148.0-1 (sid) | firefox 148.0-1 (sid) |
| debian | thunderbird | < firefox 148.0-1 (sid) | firefox 148.0-1 (sid) |
| mozilla | firefox | < 115.33.0 | 115.33.0 |
| mozilla | firefox | < 148.0 | 148.0 |
| mozilla | firefox | — | — |
| mozilla | firefox | >= 128.0 < 140.8.0 | 140.8.0 |
| mozilla | thunderbird | < 140.8.0 | 140.8.0 |
| mozilla | thunderbird | < 148.0 | 148.0 |
| mozilla | thunderbird | >= 0 < 1:140.8.0esr-1~deb11u1 | 1:140.8.0esr-1~deb11u1 |
| mozilla | thunderbird | >= 0 < 1:140.8.0esr-1~deb12u1 | 1:140.8.0esr-1~deb12u1 |
| mozilla | thunderbird | >= 0 < 1:140.8.0esr-1~deb13u1 | 1:140.8.0esr-1~deb13u1 |
| mozilla | thunderbird | >= 0 < 1:140.8.0esr-1 | 1:140.8.0esr-1 |
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: thunderbird: Undefined behavior in the DOM: Core & HTML component
vendor_redhat·2026-02-24·CVSS 9.8
CVE-2026-2771 [CRITICAL] firefox: thunderbird: Undefined behavior in the DOM: Core & HTML component
firefox: thunderbird: Undefined behavior in the DOM: Core & HTML component
Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Undefined behavior in the DOM: Core & HTML component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: rhel10/thunderbird-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: firefox (Red Hat Enterprise Linux 6) - Out of support scope
Package: thunderb
Debian
CVE-2026-2771: firefox - Undefined behavior in the DOM: Core & HTML component. This vulnerability affects...
vendor_debian·2026·CVSS 9.8
CVE-2026-2771 [CRITICAL] CVE-2026-2771: firefox - Undefined behavior in the DOM: Core & HTML component. This vulnerability affects...
Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
Scope: local
sid: resolved (fixed in 148.0-1)
Mozilla
Mozilla Foundation Security Advisory 2026-13: CVE-2026-2771
vendor_mozilla·CVSS 9.8
CVE-2026-2771 [CRITICAL] Mozilla Foundation Security Advisory 2026-13: CVE-2026-2771
Mozilla Foundation Security Advisory 2026-13
CVE: CVE-2026-2771
Product: Firefox
Impact: high
Fixed in: Firefox 148
Mozilla
Mozilla Foundation Security Advisory 2026-15: CVE-2026-2771
vendor_mozilla·CVSS 9.8
CVE-2026-2771 [CRITICAL] Mozilla Foundation Security Advisory 2026-15: CVE-2026-2771
Mozilla Foundation Security Advisory 2026-15
CVE: CVE-2026-2771
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.8
Mozilla
Mozilla Foundation Security Advisory 2026-14: CVE-2026-2771
vendor_mozilla·CVSS 9.8
CVE-2026-2771 [CRITICAL] Mozilla Foundation Security Advisory 2026-14: CVE-2026-2771
Mozilla Foundation Security Advisory 2026-14
CVE: CVE-2026-2771
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 115.33
Mozilla
Mozilla Foundation Security Advisory 2026-16: CVE-2026-2771
vendor_mozilla·CVSS 9.8
CVE-2026-2771 [CRITICAL] Mozilla Foundation Security Advisory 2026-16: CVE-2026-2771
Mozilla Foundation Security Advisory 2026-16
CVE: CVE-2026-2771
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 148
Mozilla
Mozilla Foundation Security Advisory 2026-17: CVE-2026-2771
vendor_mozilla·CVSS 9.8
CVE-2026-2771 [CRITICAL] Mozilla Foundation Security Advisory 2026-17: CVE-2026-2771
Mozilla Foundation Security Advisory 2026-17
CVE: CVE-2026-2771
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.8
OSV
CVE-2026-2771: Undefined behavior in the DOM: Core & HTML component
osv·2026-02-24·CVSS 9.8
CVE-2026-2771 [CRITICAL] CVE-2026-2771: Undefined behavior in the DOM: Core & HTML component
Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
GHSA
GHSA-m65f-px5x-xq9x: Undefined behavior in the DOM: Core & HTML component
ghsa_unreviewed·2026-02-24
CVE-2026-2771 [CRITICAL] CWE-125 GHSA-m65f-px5x-xq9x: Undefined behavior in the DOM: Core & HTML component
Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8.
No detection rules found.
No public exploits indexed.
Wiz
CVE-2026-2771 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 9.8
CVE-2026-2771 [CRITICAL] CVE-2026-2771 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-2771 :
NixOS vulnerability analysis and mitigation
Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
Source : NVD
## 9.8
Score
Published February 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) 20.4
Exploitation Probability (EPSS) 0.1
Affected packages and libraries
MozillaFirefox-devel
MozillaThunderbird-translations-other
Sources
AlmaLinux 8 Severity HIGH Has Fix Added at: Mar 03, 2026
AlmaLinux 9 Severity HIGH Has Fix Added at: Mar 02, 2026
Debian
Bugzilla
CVE-2026-72375 kernel: afs: Fix reinitialisation of the inode, in particular ->lock_work
bugzilla·2026-08-15·CVSS 7.8
CVE-2026-72375 [HIGH] CVE-2026-72375 kernel: afs: Fix reinitialisation of the inode, in particular ->lock_work
CVE-2026-72375 kernel: afs: Fix reinitialisation of the inode, in particular ->lock_work
In the Linux kernel, the following vulnerability has been resolved:
afs: Fix reinitialisation of the inode, in particular ->lock_work
It seems that initalising afs_vnode::lock_work a single time in the slab's
init function isn't sufficient for work_structs. This results in the
DEBUG_OBJECTS debugging stuff producing a warning occasionally when running
the generic/131 xfstest:
ODEBUG: activate not available (active state 0) object: 0000000016d8760f object type: work_struct hint: afs_lock_work+0x0/0x220
WARNING: lib/debugobjects.c:629 at debug_print_object+0x4b/0x90, CPU#3: locktest/7695
...
CPU: 3 UID: 0 PID: 7695 Comm: locktest Tainted: G S 7.1.0-build3+ #2771 PREEMPT
...
RIP: 0010:debug_print_obje
Bugzilla
CVE-2026-2771 firefox: thunderbird: Undefined behavior in the DOM: Core & HTML component
bugzilla·2026-02-24·CVSS 9.8
CVE-2026-2771 [CRITICAL] CVE-2026-2771 firefox: thunderbird: Undefined behavior in the DOM: Core & HTML component
CVE-2026-2771 firefox: thunderbird: Undefined behavior in the DOM: Core & HTML component
Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8.
Discussion:
This issue has been addressed in the following products:
Red Hat Enterprise Linux 8
Via RHSA-2026:3338 https://access.redhat.com/errata/RHSA-2026:3338
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9
Via RHSA-2026:3339 https://access.redhat.com/errata/RHSA-2026:3339
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 10
Via RHSA-2026:3361 https://access.redhat.com/errata/RHSA-2026:3361
---
This issue has been addressed in the following products:
Red Hat Enterpris
https://bugzilla.mozilla.org/show_bug.cgi?id=2014593https://www.mozilla.org/security/advisories/mfsa2026-13/https://www.mozilla.org/security/advisories/mfsa2026-14/https://www.mozilla.org/security/advisories/mfsa2026-15/https://www.mozilla.org/security/advisories/mfsa2026-16/https://www.mozilla.org/security/advisories/mfsa2026-17/https://access.redhat.com/errata/RHSA-2026:3338https://access.redhat.com/errata/RHSA-2026:3339https://access.redhat.com/errata/RHSA-2026:3361https://access.redhat.com/errata/RHSA-2026:3491https://access.redhat.com/errata/RHSA-2026:3492https://access.redhat.com/errata/RHSA-2026:3493https://access.redhat.com/errata/RHSA-2026:3494https://access.redhat.com/errata/RHSA-2026:3495https://access.redhat.com/errata/RHSA-2026:3496https://access.redhat.com/errata/RHSA-2026:3497https://access.redhat.com/errata/RHSA-2026:3515https://access.redhat.com/errata/RHSA-2026:3516https://access.redhat.com/errata/RHSA-2026:3517https://access.redhat.com/errata/RHSA-2026:3976https://access.redhat.com/errata/RHSA-2026:3978https://access.redhat.com/errata/RHSA-2026:3979https://access.redhat.com/errata/RHSA-2026:3980https://access.redhat.com/errata/RHSA-2026:3981https://access.redhat.com/errata/RHSA-2026:3982https://access.redhat.com/errata/RHSA-2026:3983https://access.redhat.com/errata/RHSA-2026:3984https://access.redhat.com/errata/RHSA-2026:4022https://access.redhat.com/errata/RHSA-2026:4152https://access.redhat.com/errata/RHSA-2026:4260https://access.redhat.com/errata/RHSA-2026:4432https://access.redhat.com/security/cve/CVE-2026-2771https://bugzilla.redhat.com/show_bug.cgi?id=2442288https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2771.json
2026-02-24
Published