VulnerabilityPublished 27 Oct 2026

CVE-2026-117966: Site Isolation Issue

Source GCVE Database

Authoritative record:CVE-2026-117966· High

Not known to be exploited.

Data as of 27 Oct 2026, 17:12 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-hf57-xcpv-jcvq

What to do

AI-suggested

A fix for this vulnerability is available and has been incorporated in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation actions are indicated by the vendor advisory.

Description

CVE-2026-117966 is a site isolation vulnerability in the Networking: HTTP component of Firefox. This security issue 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 the vendor. No known exploits in the wild have been reported.

Impact

The vulnerability impacts the security boundary enforced by site isolation in the Networking: HTTP component, potentially allowing unauthorized access or data leakage between sites. Mozilla rates the impact as high, indicating that exploitation could lead to significant security breaches. However, there are no known active exploits in the wild at this time.

Summary

This vulnerability concerns a site isolation issue within the Networking: HTTP component of Firefox. Site isolation is a security feature designed to separate different websites into distinct processes to prevent data leaks and cross-site attacks. The flaw could potentially undermine this isolation, leading to security risks. Mozilla fixed this vulnerability in Firefox 159 and corresponding ESR releases. The advisory classifies the impact as high, indicating a serious security concern.

References

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