CVE-2026-2766 json
Use-after-free in the JavaScript Engine: JIT component
published 2026-02-24 8 mo ago modified 2026-07-15 3 mo ago also EUVD-2026-8489
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 54%
- public exploits
- 0
- none known
Summary
Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Patch / fix
- Red Hat Red Hat Enterprise Linux 10 0:140.8.0-2.el10_1
- Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:140.8.0-2.el10_0
- Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:140.8.0-2.el7_9
- Red Hat Red Hat Enterprise Linux 8 0:140.8.0-1.el8_10, 0:140.8.0-2.el8_10
- Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support 0:140.8.0-1.el8_2, 0:140.8.0-2.el8_2
- Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:140.8.0-2.el8_4
- Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:140.8.0-2.el8_4
- Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:140.8.0-1.el8_6, 0:140.8.0-2.el8_6
- Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service 0:140.8.0-1.el8_6, 0:140.8.0-2.el8_6
- Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions 0:140.8.0-1.el8_6, 0:140.8.0-2.el8_6
- Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:140.8.0-1.el8_8, 0:140.8.0-2.el8_8
- Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:140.8.0-1.el8_8, 0:140.8.0-2.el8_8
- Red Hat Red Hat Enterprise Linux 9 0:140.8.0-1.el9_7, 0:140.8.0-2.el9_7
- Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 0:140.8.0-1.el9_0, 0:140.8.0-2.el9_0
- Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:140.8.0-1.el9_2, 0:140.8.0-2.el9_2
- Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support 0:140.8.0-1.el9_4, 0:140.8.0-2.el9_4
- Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:140.8.0-1.el9_6, 0:140.8.0-2.el9_6
- firefox-esr Debian 12 140.8.0esr-1~deb12u1
- firefox-esr Debian 13 140.8.0esr-1~deb13u1
- firefox-esr Debian 14 140.8.0esr-1
- thunderbird Debian 12 1:140.8.0esr-1~deb12u1
- thunderbird Debian 13 1:140.8.0esr-1~deb13u1
- thunderbird Debian 14 1:140.8.0esr-1
debian advisories DEBIAN-CVE-2026-2766
- thunderbird RHEL 9 140.8.0-1.el9_7
- thunderbird RHEL 10.1 140.8.0-2.el10_1
- thunderbird RHEL 8 140.8.0-1.el8_10
- firefox RHEL 10.1 140.8.0-2.el10_1
- firefox RHEL 9 140.8.0-2.el9_7
- firefox-x11 RHEL 9 140.8.0-2.el9_7
- firefox RHEL 8 140.8.0-2.el8_10
- thunderbird RHEL 8.2 AUS 140.8.0-1.el8_2
red hat advisories RHSA-2026:4432RHSA-2026:4260RHSA-2026:4152RHSA-2026:4022RHSA-2026:3976RHSA-2026:3984
- MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7, openSUSE Leap 15.6 140.8.0-150200.8.260.1
- MozillaFirefox SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +9 more 140.8.0-150200.152.222.1
- MozillaFirefox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 140.8.0-112.301.1
suse advisories SUSE-SU-2026:0880-1SUSE-SU-2026:0871-1SUSE-SU-2026:0812-1
- MozillaThunderbird openSUSE Leap 16.0 140.8.1-bp160.1.1
- MozillaFirefox openSUSE Leap 16.0 140.8.0-160000.1.1
- MozillaFirefox openSUSE Tumbleweed 148.0-1.1
- MozillaThunderbird openSUSE Tumbleweed 140.8.0-1.1
- firefox-esr openSUSE Tumbleweed 140.8.0-1.1
opensuse advisories openSUSE-SU-2026:20391-1openSUSE-SU-2026:20365-1openSUSE-SU-2026:10257-1openSUSE-SU-2026:10248-1openSUSE-SU-2026:10242-1
- thunderbird AlmaLinux 8 140.8.0-1.el8_10.alma.1
- thunderbird AlmaLinux 9 140.8.0-1.el9_7.alma.1
- thunderbird AlmaLinux 10 140.8.0-2.el10_1.alma.1
- firefox AlmaLinux 8 140.8.0-2.el8_10.alma.1
- firefox AlmaLinux 9 140.8.0-2.el9_7.alma.1
- firefox-x11 AlmaLinux 9 140.8.0-2.el9_7.alma.1
- firefox AlmaLinux 10 140.8.0-2.el10_1
almalinux advisories ALSA-2026:3515ALSA-2026:3516ALSA-2026:3517ALSA-2026:3338ALSA-2026:3339ALSA-2026:3361
- thunderbird Rocky Linux 10 140.8.0-2.el10_1
- thunderbird Rocky Linux 9 140.8.0-1.el9_7
- thunderbird Rocky Linux 8 140.8.0-1.el8_10
- firefox Rocky Linux 10 140.8.0-2.el10_1
- firefox Rocky Linux 9 140.8.0-2.el9_7
- firefox Rocky Linux 8 140.8.0-2.el8_10
rocky linux advisories RLSA-2026:3517RLSA-2026:3516RLSA-2026:3515RLSA-2026:3361RLSA-2026:3339RLSA-2026:3338
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-2766 updated cvss 7.5
firefox: thunderbird: Use-after-free in the JavaScript Engine: JIT component
-
Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 thunderbirdaffected: no fix planned “Out of support scope”
-
Red Hat Enterprise Linux 10 rhel10/firefox-flatpak, rhel10/thunderbird-flatpakaffected: no fix available
-
Red Hat Enterprise Linux AppStream (v. 8) firefox 140.8.0-2.el8_10, thunderbird 140.8.0-1.el8_10fixed: vendor fix RHSA-2026:3338
-
Red Hat Enterprise Linux AppStream (v. 9) firefox 140.8.0-2.el9_7, firefox-x11 140.8.0-2.el9_7, thunderbird 140.8.0-1.el9_7fixed: vendor fix RHSA-2026:3339
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Red Hat Enterprise Linux AppStream (v. 10) firefox 140.8.0-2.el10_1, thunderbird 140.8.0-2.el10_1fixed: vendor fix RHSA-2026:3361
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Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox 140.8.0-2.el8_2, thunderbird 140.8.0-1.el8_2fixed: vendor fix RHSA-2026:3492
-
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 140.8.0-2.el8_4, thunderbird 140.8.0-2.el8_4fixed: vendor fix RHSA-2026:3491
-
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 140.8.0-2.el8_6, thunderbird 140.8.0-1.el8_6 Red Hat Enterprise Linux AppStream E4S (v.8.6) firefox 140.8.0-2.el8_6, thunderbird 140.8.0-1.el8_6fixed: vendor fix RHSA-2026:3495
show 10 moreshow fewer
-
Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 140.8.0-2.el8_8, thunderbird 140.8.0-1.el8_8fixed: vendor fix RHSA-2026:3494
-
Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 140.8.0-2.el9_0, thunderbird 140.8.0-1.el9_0fixed: vendor fix RHSA-2026:3493
-
Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 140.8.0-2.el9_2, firefox-x11 140.8.0-2.el9_2, thunderbird 140.8.0-1.el9_2fixed: vendor fix RHSA-2026:4152
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Red Hat Enterprise Linux AppStream EUS (v. 10.0) firefox 140.8.0-2.el10_0, thunderbird 140.8.0-2.el10_0fixed: vendor fix RHSA-2026:3976
-
Red Hat Enterprise Linux AppStream EUS (v.9.4) firefox 140.8.0-2.el9_4, firefox-x11 140.8.0-2.el9_4, thunderbird 140.8.0-1.el9_4fixed: vendor fix RHSA-2026:3496
-
Red Hat Enterprise Linux AppStream EUS (v.9.6) firefox 140.8.0-2.el9_6, firefox-x11 140.8.0-2.el9_6, thunderbird 140.8.0-1.el9_6fixed: vendor fix RHSA-2026:3497
-
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 140.8.0-2.el8_4, thunderbird 140.8.0-2.el8_4fixed: vendor fix RHSA-2026:3491
-
Red Hat Enterprise Linux AppStream TUS (v.8.6) firefox 140.8.0-2.el8_6, thunderbird 140.8.0-1.el8_6fixed: vendor fix RHSA-2026:3495
-
Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 140.8.0-2.el8_8, thunderbird 140.8.0-1.el8_8fixed: vendor fix RHSA-2026:3494
-
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.8.0-2.el7_9fixed: vendor fix RHSA-2026:3984
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 8 mo ago
Exploit prediction
0.74% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CISA ADP | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H |
Affected products
- Mozilla Firefox
- Mozilla Thunderbird
- Red Hat Red Hat Enterprise Linux 10
- Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
- Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support
- Red Hat Red Hat Enterprise Linux 8
- Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support
- Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
- Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
- Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
- Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service
- Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
- Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
- Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
- Red Hat Red Hat Enterprise Linux 9
- Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
- Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
- Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support
- Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
- Red Hat Red Hat Enterprise Linux 6
- Red Hat Red Hat Enterprise Linux 7
Classification
- Weakness
-
- CWE-416 Use After Free
References
-
access.redhat.com
/errata/RHSA-2026:3984
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3976
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:4260
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3361
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3517
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3338
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3515
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3492
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:4432
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3491
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3980
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3495
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3979
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3494
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:4022
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3493
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3983
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:4152
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3978
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3496
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3981
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3497
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3982
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3339
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:3516
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-13/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-15/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-16/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-17/
vendor-advisory
-
bugzilla.mozilla.org
/show_bug.cgi?id=2013583
issue-tracking, permissions-required
-
access.redhat.com
/security/cve/CVE-2026-2766
vdb-entry
-
bugzilla.redhat.com
/show_bug.cgi?id=2442294
issue-tracking
- security.access.redhat.com /data/csaf/v2/vex/2026/cve-2026-2766.json
Sources
- CVE List CVE-2026-2766
- NVD CVE-2026-2766
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.