ComfyUI-Copilot EUVD-2026-39992

Exploitation requires an active authenticated session on the ComfyUI-Copilot instance (PR:L) - the attacker must possess a valid session token for the same deployment being targeted. The attacker must additionally enumerate or predict valid integer version_id or checkpoint_id values belonging to other sessions; the high attack complexity (AC:H) in the CVSS 4.0 vector directly reflects this enumeration prerequisite. Exploitation is limited to reading or overwriting workflow checkpoint configuration data (VC:L); no integrity impact on other systems (VI:N, VA:N, SC:N, SI:N, SA:N) is possible via this vector. No special non-default configuration is required on the victim deployment beyond having multiple active sessions with saved checkpoints. Single-user or local-only ComfyUI-Copilot installations without network-accessible backends are not reachable by remote attackers.

The CVSS 4.0 vector (AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P) yields a base score of 2.3, reflecting the combination of network accessibility offset by high attack complexity and limited confidentiality-only impact. The E:P suffix (exploit publicly available) increases practical urgency compared to unexploited issues at the same base score, but does not override the fundamental exploitation constraint: the attacker must hold a valid authenticated session (PR:L) and must be able to enumerate or predict valid integer version_id values from other active sessions - the AC:H rating directly captures this enumeration difficulty. There is no CISA KEV listing and no EPSS score was provided in the input data; absence of KEV suggests no confirmed widespread active exploitation. Real-world risk is further bounded by the nature of exposed data - workflow checkpoint configuration - rather than credentials or PII. For shared multi-tenant deployments, this is a meaningful data isolation failure; for single-user local installations, risk is negligible. Overall: low priority for most deployments, moderate priority for shared or multi-user hosted instances.

An authenticated user on a shared ComfyUI-Copilot deployment enumerates valid integer version_id values - for example by incrementing from their own checkpoint IDs - and issues crafted HTTP requests to the restore_workflow_checkpoint endpoint supplying those foreign identifiers. Because the handler performs no session ownership check, the server returns the target session's full workflow checkpoint data including workflow_data_ui configuration. A public proof-of-concept demonstrating this technique is available at https://github.com/AIDC-AI/ComfyUI-Copilot/issues/149.