CVE-2026-2776 json
Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software
published 8mo ago modified 3mo ago also EUVD-2026-8498
- cvss
- 10.0
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 47%
- public exploits
- 0
- none known
Summary
Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, 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-2026-2776
- 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
Is CVE-2026-2776 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerVendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-2776 updated cvss 7.5
firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software
-
Red Hat Enterprise Linux 6 firefox, rhel10/thunderbird-flatpak Red Hat Enterprise Linux 7 rhel10/thunderbird-flatpakaffected: no fix planned “Out of support scope”
-
Red Hat Enterprise Linux 10 rhel8/flatpak-runtime, rhel10/firefox-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
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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
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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
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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
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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
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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
- 8mo ago
Exploit prediction
0.56% chance of exploitation in the next 30 days, higher than 47% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| CNA | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
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/mfsa2026-14/
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=2015266
issue-tracking, permissions-required
-
access.redhat.com
/security/cve/CVE-2026-2776
vdb-entry
-
bugzilla.redhat.com
/show_bug.cgi?id=2442291
issue-tracking
- security.access.redhat.com /data/csaf/v2/vex/2026/cve-2026-2776.json
Sources
- CVE List CVE-2026-2776
- NVD CVE-2026-2776
Fencer Intel 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.