OpenClaw EUVD-2026-87516

Requires the attacker to already possess a valid webhook route secret for an OpenClaw deployment (PR:L) and to supply a valid child session key belonging to an ACP or subagent task outside that route's configured authority. Exploitation is limited by: the need for that pre-shared route secret, high attack complexity and a present attack requirement (AC:H/AT:P) in guessing or obtaining a valid target session key, and the fact that the only achievable effect is cancelling another session (availability disruption) - no data disclosure or modification is possible. Affects OpenClaw versions before 2026.8.1.

This is a low-priority issue despite carrying an 'Authentication Bypass' tag. The vendor CVSS 4.0 vector (CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L) yields only 2.3, and every signal reinforces low real-world risk: impact is availability-only (VC:N/VI:N/VA:L) - the flaw lets an attacker cancel sessions, not read, alter, or exfiltrate data. Exploitation is gated behind possession of a valid webhook route secret (PR:L), a non-trivial attack requirement (AT:P), and high complexity (AC:H) because the attacker must supply a valid but unrelated child session key. There is no EPSS score, no CISA KEV listing, and no public POC, so there is no evidence of exploitation. Data is internally consistent - the network vector, low privilege-with-secret, and availability-only impact all align with the CWE-639 (authorization bypass through user-controlled key / IDOR) classification. No conflicting signals to flag; the main caveat is that this is a vendor/VulnCheck-sourced score with no independent NVD analysis yet.

An attacker who already holds a webhook route secret for one OpenClaw route sends a cancellation request but substitutes a child session key belonging to an unrelated ACP or subagent task. Because the handler does not verify the target session falls within the route's configured authority, the unrelated session is cancelled, disrupting another user's or route's in-flight agent work. No public exploit code is available and the impact is limited to work disruption.