VulnerabilityPublished 27 Oct 2026

CVE-2026-117928: Same-origin Policy Bypass

Source GCVE Database

Authoritative record:CVE-2026-117928· 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-rm3p-8c93-r9fw

What to do

AI-suggested

This vulnerability has been fixed in Firefox 159 and Firefox ESR 153.6. Users and administrators should update their Firefox installations to these versions or later to mitigate the risk. No additional mitigation steps are required beyond applying the official update.

Description

CVE-2026-117928 is a same-origin policy bypass vulnerability in the CSS Parsing and Computation component of Firefox. This security flaw could allow an attacker to bypass the browser's same-origin policy, potentially leading to unauthorized access to sensitive information across origins. The issue was addressed and fixed in Firefox version 159 and Firefox ESR 153.6.

Impact

The impact of this vulnerability is high because it allows bypassing the same-origin policy, which can lead to unauthorized access to sensitive information from other origins. This undermines the fundamental security boundary enforced by browsers, potentially exposing user data or enabling further attacks.

Summary

This vulnerability involves a bypass of the same-origin policy within the CSS Parsing and Computation component of Firefox. The same-origin policy is a critical security mechanism that restricts how documents or scripts loaded from one origin can interact with resources from another origin. Bypassing this policy can lead to unauthorized cross-origin data access. Mozilla fixed this vulnerability in Firefox 159 and Firefox ESR 153.6, as documented in their security advisory MFSA 2026-118.

References

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