Skip to main content
CVE-2026-5731VulnerabilityPublished Updated

Red Hat Security Advisory: firefox security update

Affects Red Hat firefoxSource GCVE Database

0
Compare

Mentioned vulnerabilities

Authoritative record:CVE-2026-5731· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in Red Hat package updates : patch Red Hat firefox as a priority.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 140.9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Red Hatredhat/firefoxpkg:rpm/redhat/firefoxOther threatsAffected
  • =140.9.1-2.el7_9
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat has released updated Firefox packages for Red Hat Enterprise Linux 7 Extended Lifecycle Support that fix these vulnerabilities. Users should apply the Firefox update to version 140.9.1-2.el7_9 or later as provided by Red Hat. For detailed update instructions, refer to the Red Hat advisory at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the official update.

Description

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability. Security Fix(es): * libpng: libpng: Arbitrary code execution due to use-after-free vulnerability (CVE-2026-33416) * libpng: libpng: Information disclosure and denial of service via out-of-bounds read/write in Neon palette expansion (CVE-2026-33636) * thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 (CVE-2026-5734) * thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 (CVE-2026-5731) * firefox: thunderbird: Incorrect boundary conditions, integer overflow in the Graphics: Text component (CVE-2026-5732) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

References

Community reviews

Loading reviews…