Description

Insufficient validation of untrusted input in Workers in Google Chrome prior to 151.0.7922.109 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page. (Chromium security severity: High)

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-08-06T22:16:57.547Z",
  "pubdate": "2026-08-06T22:16:57.547Z",
  "executiveSummary": "An insufficient validation vulnerability exists within Workers in Google Chrome prior to version 151.0.7922.109, leading to a critical security bypass of Chromium site isolation boundaries.\nThe vulnerability allows a remote attacker who has already successfully compromised the renderer process to escape domain sandboxing and site isolation controls by utilizing a specially crafted HTML page.\nThis flaw directly impacts the security architecture of Google Chrome by undermining origin separation mechanisms designed to isolate cross-site data.\nThe risk implications are severe, as compromising the renderer process combined with this site isolation bypass can facilitate unauthorized cross-site data access and escalate privileges within the context of the browser architecture.\nSuccessful exploitation requires the attacker to have prior execution capabilities within the renderer process, typically achieved by chaining this vulnerability with an initial remote code execution or memory corruption flaw in the rendering engine.\nUsers and administrators must update Google Chrome to version 151.0.7922.109 or later to remediate the underlying validation weakness in the Workers component.",
  "technicalDetails": "The vulnerability resides in the Workers subsystem of Google Chrome prior to version 151.0.7922.109, specifically stemming from insufficient validation of untrusted input processed across process boundaries.\nIn the Chromium architecture, site isolation enforces strict separation between different origins, running them in distinct renderer processes sandbox-restricted from accessing unauthorized cross-site resources.\nThe root cause involves inadequate input sanitization and verification logic when handling messages or states associated with Workers, permitting malicious manipulation of internal IPC or shared data structures.\nAn attacker initiates the attack flow by first compromising the renderer process via a distinct exploitation vector, establishing code execution within the restricted sandbox.\nOnce execution is achieved inside the compromised renderer process, the attacker deploys a crafted HTML page containing malicious Worker instantiations designed to interact with the vulnerable validation routines.\nDue to the insufficient validation of untrusted input within the Workers component, the crafted payload tricks the browser into mishandling origin boundaries and security contexts.\nThis operational failure allows the attacker to bypass site isolation mechanisms, breaching the security perimeter intended to segregate data and execution contexts between distinct web origins.\nNo authentication or elevated privileges beyond an initial renderer compromise are required for the payload to trigger the validation bypass.\nPost-exploitation impact includes the potential unauthorized access to sensitive cross-origin data, undermining the core security guarantees provided by Chromium site isolation."
}