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Fencer Vulns
critical 9.8

CVE-2026-6748 json

Uninitialized memory in the Audio/Video: Web Codecs component

published 2026-04-21 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-24089

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:140.10.0-1.el10_1, 0:140.10.0-1.el10_2
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:140.10.0-1.el10_0
  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:140.10.0-2.el7_9
  • Red Hat Red Hat Enterprise Linux 8 0:140.10.0-1.el8_10
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:140.10.0-1.el8_4
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:140.10.0-1.el8_4
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:140.10.0-1.el8_6
  • Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service 0:140.10.0-1.el8_6
  • Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions 0:140.10.0-1.el8_6
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:140.10.0-1.el8_8
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:140.10.0-1.el8_8
  • Red Hat Red Hat Enterprise Linux 9 0:140.10.0-1.el9_7, 0:140.10.0-1.el9_8, 0:140.10.1-1.el9_8
  • Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 0:140.10.0-1.el9_0
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:140.10.0-1.el9_2
  • Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support 0:140.10.0-1.el9_4
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:140.10.0-1.el9_6
  • 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-2026-6748

  • 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-2026-6748 updated cvss 7.5

firefox: thunderbird: Uninitialized memory in the Audio/Video: Web Codecs component

  • Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 10 rhel10/firefox-flatpak, rhel10/thunderbird-flatpak
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 140.10.0-1.el8_10, thunderbird 140.10.0-1.el8_10
    fixed: 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_8
    fixed: 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_2
    fixed: 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_4
    fixed: 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_6
    fixed: 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_8
    fixed: vendor fix RHSA-2026:17477
show 9 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 140.10.0-1.el9_0, thunderbird 140.10.0-1.el9_0
    fixed: 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_2
    fixed: 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_0
    fixed: 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_4
    fixed: 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_6
    fixed: 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_4
    fixed: 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_6
    fixed: 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_8
    fixed: vendor fix RHSA-2026:17477
  • Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.10.0-2.el7_9
    fixed: 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
yes
Technical impact
total
Assessed
6 mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% 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
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 8.4 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-457 Use of Uninitialized Variable
  • CWE-824 Access of Uninitialized Pointer

References

Sources

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.