CVE-2026-100801: Privilege Escalation
Source GCVE Database
Not known to be exploited · CVSS 8.8 High · fixed in 153.4 : patch Thunderbird soon.
Data as of 27 Oct 2026, 17:12 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 153.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 29 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
AI-suggested
Apply the official fixes provided by Mozilla by upgrading to Firefox ESR 153.4, Firefox 157, or Firefox ESR 140.17 or later. These versions contain the patch that resolves this privilege escalation vulnerability. No additional mitigation is required once the update is applied.
Description
CVE-2026-100801 is a high-severity privilege escalation vulnerability in the DLL Services component of Firefox. It allows an attacker to escalate privileges, potentially leading to full control over the affected system. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
References
- nvd.nist.gov/vuln/detail/CVE-2026-100801 (opens in a new tab)
- bugzilla.mozilla.org/show_bug.cgi?id=2057112 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-100 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-101 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-102 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-103 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-118 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-120 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-97 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-99 (opens in a new tab)