Red Hat Security Advisory: firefox security update
Affects Red Hat firefoxSource GCVE Database
Mentioned vulnerabilities
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, 21:35 UTC
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 7 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 30 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Red Hat Product Security Red Hat | Affected
| Fixed in– |
AI-suggested
Security fixes have been released in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2, and Thunderbird 149.0.2. Users and administrators should update to these versions to remediate the vulnerabilities. No additional mitigation steps are indicated in the advisory.
Description
Multiple security vulnerabilities affecting Mozilla Firefox and Thunderbird have been addressed in recent updates. These include arbitrary code execution due to a use-after-free in libpng, information disclosure and denial of service via out-of-bounds read/write in libpng's Neon palette expansion, and several memory safety bugs and integer overflow issues in Firefox and Thunderbird components.
References
- access.redhat.com/errata/RHSA-2026:13596 (opens in a new tab)
- access.redhat.com/security/updates/classification/ (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2451805 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2451819 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2455897 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2455901 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2455908 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_13596.json (opens in a new tab)