CVE-2026-6763 json
Mitigation bypass in the File Handling component
published 2026-04-21 6 mo ago modified 2026-10-26 14 d ago also EUVD-2026-24104
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 8%
- public exploits
- 0
- none known
Summary
Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
Patch / fix
- mozilla firefox 140.10.0, 150.0
- mozilla thunderbird 140.10.0
- firefox-esr Debian 12 140.10.0esr-1~deb12u1
- firefox-esr Debian 13 140.10.0esr-1~deb13u1
- firefox-esr Debian 14 140.10.0esr-1
- thunderbird Debian 12 1:140.10.0esr-1~deb12u1
- thunderbird Debian 13 1:140.10.0esr-1~deb13u1
- thunderbird Debian 14 1:140.10.0esr-1
debian advisories DEBIAN-CVE-2026-6763
- thunderbird RHEL 9 140.10.1-1.el9_8
- firefox RHEL 9 140.10.0-1.el9_8
- firefox-x11 RHEL 9 140.10.0-1.el9_8
- thunderbird RHEL 10.2 140.10.0-1.el10_2
- firefox RHEL 10.2 140.10.0-1.el10_2
- thunderbird RHEL 9 140.10.0-1.el9_7
- thunderbird RHEL 8 140.10.0-1.el8_10
- thunderbird RHEL 10.1 140.10.0-1.el10_1
red hat advisories RHSA-2026:19704RHSA-2026:19655RHSA-2026:19542RHSA-2026:19469RHSA-2026:19467RHSA-2026:19468
- firefox-esr openSUSE Tumbleweed 153.0-1.1
- MozillaFirefox openSUSE Tumbleweed 150.0-1.1
- MozillaThunderbird openSUSE Tumbleweed 140.9.1-1.1
opensuse advisories openSUSE-SU-2026:11373-1openSUSE-SU-2026:10626-1openSUSE-SU-2026:10610-1
- thunderbird AlmaLinux 9 140.10.1-1.el9_8.alma.1
- thunderbird AlmaLinux 9 140.10.0-1.el9_7.alma.1
- thunderbird AlmaLinux 8 140.10.0-1.el8_10.alma.1
- thunderbird AlmaLinux 10 140.10.0-1.el10_1.alma.1
- firefox AlmaLinux 9 140.10.0-1.el9_7.alma.1
- firefox-x11 AlmaLinux 9 140.10.0-1.el9_7.alma.1
- firefox AlmaLinux 8 140.10.0-1.el8_10.alma.1
- firefox AlmaLinux 10 140.10.0-1.el10_1
almalinux advisories ALSA-2026:19348ALSA-2026:15892ALSA-2026:13537ALSA-2026:12285ALSA-2026:10757ALSA-2026:10766
- thunderbird Rocky Linux 9 140.10.1-1.el9_8
- firefox Rocky Linux 9 140.10.0-1.el9_7
- thunderbird Rocky Linux 9 140.10.0-1.el9_7
- thunderbird Rocky Linux 10 140.10.0-1.el10_1
- thunderbird Rocky Linux 8 140.10.0-1.el8_10
- firefox Rocky Linux 8 140.10.0-1.el8_10
- firefox Rocky Linux 10 140.10.0-1.el10_1
rocky linux advisories RLSA-2026:19348RLSA-2026:19201RLSA-2026:15892RLSA-2026:12285RLSA-2026:13537RLSA-2026:10766
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-2026-6763 updated cvss 6.1
firefox: thunderbird: Mitigation bypass in the File Handling 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 140.10.0-1.el8_10, thunderbird 140.10.0-1.el8_10fixed: vendor fix RHSA-2026:10766
-
Red Hat Enterprise Linux AppStream (v. 9) firefox 140.10.0-1.el9_7, firefox 140.10.0-1.el9_8, firefox-x11 140.10.0-1.el9_7, firefox-x11 140.10.0-1.el9_8, thunderbird 140.10.0-1.el9_7, thunderbird 140.10.1-1.el9_8fixed: vendor fix RHSA-2026:10757
-
Red Hat Enterprise Linux AppStream (v. 10) firefox 140.10.0-1.el10_1, firefox 140.10.0-1.el10_2, thunderbird 140.10.0-1.el10_1, thunderbird 140.10.0-1.el10_2fixed: vendor fix RHSA-2026:10767
-
Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 140.10.0-1.el8_4, thunderbird 140.10.0-1.el8_4fixed: vendor fix RHSA-2026:19655
-
Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 140.10.0-1.el8_6, thunderbird 140.10.0-1.el8_6 Red Hat Enterprise Linux AppStream E4S (v.8.6) firefox 140.10.0-1.el8_6, thunderbird 140.10.0-1.el8_6fixed: vendor fix RHSA-2026:19542
-
Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 140.10.0-1.el8_8, thunderbird 140.10.0-1.el8_8fixed: vendor fix RHSA-2026:17477
show 9 moreshow fewer
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Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 140.10.0-1.el9_0, thunderbird 140.10.0-1.el9_0fixed: vendor fix RHSA-2026:17687
-
Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 140.10.0-1.el9_2, firefox-x11 140.10.0-1.el9_2, thunderbird 140.10.0-1.el9_2fixed: vendor fix RHSA-2026:17689
-
Red Hat Enterprise Linux AppStream EUS (v. 10.0) firefox 140.10.0-1.el10_0, thunderbird 140.10.0-1.el10_0fixed: vendor fix RHSA-2026:17690
-
Red Hat Enterprise Linux AppStream EUS (v.9.4) firefox 140.10.0-1.el9_4, firefox-x11 140.10.0-1.el9_4, thunderbird 140.10.0-1.el9_4fixed: vendor fix RHSA-2026:19464
-
Red Hat Enterprise Linux AppStream EUS (v.9.6) firefox 140.10.0-1.el9_6, firefox-x11 140.10.0-1.el9_6, thunderbird 140.10.0-1.el9_6fixed: vendor fix RHSA-2026:17688
-
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 140.10.0-1.el8_4, thunderbird 140.10.0-1.el8_4fixed: vendor fix RHSA-2026:19655
-
Red Hat Enterprise Linux AppStream TUS (v.8.6) firefox 140.10.0-1.el8_6, thunderbird 140.10.0-1.el8_6fixed: vendor fix RHSA-2026:19542
-
Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 140.10.0-1.el8_8, thunderbird 140.10.0-1.el8_8fixed: vendor fix RHSA-2026:17477
-
Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.10.0-2.el7_9fixed: vendor fix RHSA-2026:19704
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
- no
- Technical impact
- partial
- Assessed
- 6 mo ago
Exploit prediction
0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
Affected products
- Mozilla Firefox
- Mozilla Thunderbird
Classification
- Weakness
-
- CWE-693 Protection Mechanism Failure
References
-
mozilla.org
/security/advisories/mfsa2026-30/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-32/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-33/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2026-34/
vendor-advisory
-
bugzilla.mozilla.org
/show_bug.cgi?id=2021666
permissions-required
Sources
- CVE List CVE-2026-6763
- NVD CVE-2026-6763
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