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Fencer Vulns
high 8.8

CVE-2026-117883 json

Use-after-free in the DOM: HTML Parser component

published 2026-10-27 13 d ago modified 2026-11-04 4 d ago also EUVD-2026-111054

cvss
8.8
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

Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.

Patch / fix

  • mozilla firefox 115.44, 153.6, 159
  • mozilla firefox_esr 115.44, 153.6, 159
  • mozilla thunderbird 153.6, 159
  • mozilla thunderbird_esr 153.6, 159
  • firefox-esr Debian 12 153.6.0esr-1~deb12u2
  • firefox-esr Debian 13 153.6.0esr-1~deb13u1
  • thunderbird Debian 12 1:153.6.0esr-1~deb12u2
  • thunderbird Debian 13 1:153.6.0esr-1~deb13u1

debian advisories DEBIAN-CVE-2026-117883

  • MozillaFirefox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 153.6.0-118.19.2

suse advisories SUSE-SU-2026:4928-1

  • MozillaThunderbird openSUSE Tumbleweed 153.6.0-1.1
  • firefox-esr openSUSE Tumbleweed 153.6.0-1.1

opensuse advisories openSUSE-SU-2026:12339-1openSUSE-SU-2026:12319-1

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-2026-117883 updated cvss 7.5

firefox: thunderbird: Use-after-free in the DOM: HTML Parser component

  • Red Hat Enterprise Linux 6 firefox, thunderbird
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 firefox, thunderbird
    affected: workaround, no fix available, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 firefox, thunderbird Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird Red Hat Enterprise Linux 10 firefox, thunderbird, rhel10/firefox-flatpak, rhel10/thunderbird-flatpak
    affected: workaround, no fix available

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
total
Assessed
4 d 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 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • Mozilla Firefox
  • Mozilla Thunderbird

Classification

Weakness

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.