VulnerabilityPublished 27 Oct 2026

CVE-2026-117943: Mozilla Firefox · Use-after-free in the DOM: Core & HTML component

Affects Mozilla FirefoxSource CVE Database V5

Not known to be exploited.

Data as of 27 Oct 2026, 17:24 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Oct 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

A fix for this vulnerability is available in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6. Users and administrators should update to these versions or later to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory.

Description

CVE-2026-117943 is a use-after-free vulnerability in the DOM Core & HTML component of Mozilla Firefox. This security flaw was addressed and fixed in Firefox version 159 and Firefox ESR versions 115.44 and 153.6. The vulnerability is rated with high impact by Mozilla, indicating serious security concerns if exploited. There are no known exploits in the wild as of the advisory date.

Impact

The vulnerability has a high impact rating, implying that successful exploitation could lead to significant security consequences such as arbitrary code execution or browser compromise. However, no known exploitation in the wild has been reported at the time of the advisory.

Summary

This vulnerability involves a use-after-free condition in the DOM Core & HTML component of Firefox, which could potentially allow an attacker to execute arbitrary code or cause a crash. Mozilla fixed this issue in Firefox 159 and corresponding ESR releases 115.44 and 153.6. The advisory is part of a broader set of memory safety vulnerabilities addressed simultaneously. No active exploitation has been reported.

References

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 27 Oct 2026, 15:12 UTC

Technical details

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