Google Cloud Shell CVE-2026-85267

Exploitation requires two specific preconditions: (1) the victim must have an active, authenticated Google Cloud Shell session open, and (2) the victim must be induced to load an attacker-controlled web page that issues a cross-origin WebSocket request (the UI:P passive-interaction factor in the CVSS vector). The underlying technical condition is the Cloud Shell WebSocket endpoint's failure to validate the request Origin (CWE-1385). The attacker needs no credentials or prior access (PR:N). Limiting factors: the required user interaction and the need for a concurrently active session narrow the window, and because Google deployed a server-side fix on 2026-07-22 the vulnerable code path no longer exists in the hosted service - there is no on-premises or customer-patchable component.

This is a genuinely high-risk design flaw, but with important real-world caveats. The CVSS 4.0 base score of 8.7 is driven by a network attack vector (AV:N), low complexity (AC:L), no attacker privileges (PR:N), and high impact to confidentiality, integrity, and availability - justified because a stolen OAuth access token effectively grants the attacker the victim's Cloud Shell identity. The single factor that meaningfully constrains exploitation is the passive user-interaction requirement (UI:P): the victim must have an active Cloud Shell session and be lured to an attacker-controlled web page that issues the cross-origin WebSocket request. No EPSS score, CISA KEV listing, or public POC is present in the provided data, so by the precision rules this is classified as 'no public exploit identified at time of analysis' - the elevated score reflects latent potential and the sensitivity of the OAuth token, not observed exploitation. Crucially, the vendor states the flaw was fixed server-side on 2026-07-22 with no customer action required, so for the hosted Cloud Shell service the practical residual risk today is effectively zero; the analytical risk applies to the pre-patch window. No signals conflict, though note the CVSS 4.0 subsequent-system metrics (SC/SI/SA:L) imply the token enables impact on resources beyond Cloud Shell itself.

A victim with an active Google Cloud Shell session is tricked into visiting a malicious web page (satisfying the UI:P requirement). The page opens a cross-origin WebSocket connection to the Cloud Shell backend, which fails to validate the request origin (CWE-1385), hijacking the session and exfiltrating the user's OAuth access token to the attacker. No public exploit code is identified in the provided data, and Google reports the issue was fixed server-side on 2026-07-22.