Red Hat Quay EUVD-2026-35044

The attacker must be authenticated to the Quay instance and hold write access to at least one repository (PR:L per CVSS). The filedrop endpoint must be accessible to the attacker's account. A victim user must visit the specific CDN-hosted archive URL containing the malicious SVG (UI:R per CVSS) - the attacker cannot trigger execution automatically or remotely without victim interaction. Exploitation is further limited to Red Hat Quay 3.x deployments; Quay instances that serve uploaded files with a forced download Content-Disposition header rather than inline rendering would not be exploitable via this path. Deployments where the filedrop endpoint is disabled, rate-limited, or restricted to trusted service accounts substantially reduce exposure.

The CVSS 5.4 Medium score is derived from a network attack vector (AV:N), low complexity (AC:L), low-privilege authentication requirement (PR:L), required user interaction (UI:R), changed scope (S:C), and low confidentiality and integrity impacts (C:L/I:L/A:N). The PR:L requirement confirms this is not an unauthenticated attack - the adversary must already hold repository write access within the Quay instance. UI:R further constrains exploitability, as a victim must actively visit the malicious archive URL; the attacker cannot force this. No EPSS score was provided in the source data, preventing quantitative exploitation-probability comparison. The vulnerability is not listed in the CISA KEV catalog, and no public proof-of-concept has been identified. Taken together, the real-world risk is moderate: the attack surface is meaningfully narrowed by the authentication and user-interaction prerequisites, and the impact is bounded to low confidentiality and integrity (e.g., session token theft, UI defacement). The Changed Scope rating, however, elevates concern in multi-tenant deployments where a single compromised account could target higher-privileged users such as administrators. The specific version range affected is not bounded in the CPE data (wildcard), meaning all Quay 3.x releases should be treated as vulnerable until a patched version is confirmed.

An attacker with repository write access to a Quay 3.x instance crafts an SVG file containing a JavaScript payload designed to exfiltrate session cookies or perform actions on behalf of the victim. The attacker uploads the file via the filedrop endpoint, then socially engineers or waits for a higher-privileged user (e.g., an organization administrator) to visit the archive URL. When the victim's browser renders the SVG inline from the CDN, the JavaScript executes in the Quay origin context, enabling session hijacking or credential theft. No public proof-of-concept code has been identified, but the attack technique is well-understood and low-complexity for anyone with repository write access.