VulnerabilityPublished 27 Oct 2026

CVE-2026-117920: Use-after-free in the DOM · HTML Parser component

Source GCVE Database

Authoritative record:CVE-2026-117920· High

Not known to be exploited.

Data as of 27 Oct 2026, 17:58 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.

ghsa-rqr3-4wvw-wvm2

What to do

AI-suggested

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

Description

CVE-2026-117920 is a use-after-free vulnerability in the DOM HTML Parser component of Firefox. This security flaw was addressed and fixed in Firefox version 159 and Firefox ESR 153.6. The vulnerability is rated with high impact by the vendor. No known exploits in the wild have been reported. Users are advised to update to the fixed versions to mitigate the risk.

Impact

The vulnerability could allow an attacker to exploit memory corruption in the HTML Parser component, potentially leading to arbitrary code execution or browser compromise. The vendor rates the impact as high, reflecting the severity of use-after-free issues in browser components. However, no active exploitation has been reported.

Summary

This vulnerability involves a use-after-free condition in the DOM HTML Parser component of Firefox. Use-after-free vulnerabilities occur when a program continues to use a pointer after the memory it points to has been freed, potentially leading to memory corruption and security issues. Mozilla fixed this vulnerability in Firefox 159 and Firefox ESR 153.6. The advisory classifies the impact as high, indicating a serious security concern. There is no indication of active exploitation in the wild at this time.

References

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