CVE-2026-41395: 
OpenClaw (formerly Moltbot or Clawdbot) vulnerability analysis and mitigation

CVE-2026-41395 is a webhook replay vulnerability in OpenClaw's Plivo V3 signature verification mechanism, allowing attackers to bypass replay cache detection by reordering query parameters and trigger duplicate voice-call processing. It affects OpenClaw versions up to and including 2026.3.24 (Node.js package on npm), with the fix introduced in version 2026.3.28. The vulnerability was published on April 28, 2026. It carries a CVSS v3.1 base score of 7.5 (High) and a CVSS v4.0 base score of 8.2 (High) (GitHub Advisory, VulnCheck).

The root cause is classified as CWE-325 (Missing Cryptographic Step): the Plivo V3 signature verification in extensions/voice-call/src/webhook-security.ts canonicalizes (sorts) query parameters before computing the HMAC signature, but the replay detection cache hashes the raw, unsorted URL. This inconsistency means that reordering query parameters in a captured valid webhook produces an identical valid signature (since signature verification normalizes the order) while generating a distinct cache key (since replay detection does not normalize the order), effectively bypassing the replay protection. An attacker must first capture a legitimately signed Plivo V3 webhook — a prerequisite that requires network interception or access to webhook traffic — and then replay it with permuted query parameters (GitHub Advisory).

Successful exploitation allows an attacker who has captured a single valid signed Plivo V3 webhook to replay it an arbitrary number of times by permuting query parameters, causing duplicate voice-call processing events. The primary impact is an integrity violation: unauthorized repeated execution of business logic tied to voice-call webhooks, which could result in unintended repeated actions, billing fraud, or business logic bypasses. There is no confidentiality or availability impact reported (GitHub Advisory, VulnCheck).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (VulnCheck). The EPSS score is approximately 0.02%, reflecting a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires a precondition — possession of a captured valid signed webhook — which limits the attacker pool but does not require any privileges on the target system itself.

1. Capture a valid signed webhook: Intercept or otherwise obtain a legitimate Plivo V3 webhook request sent to an OpenClaw instance (e.g., via network interception, a compromised intermediary, or access to webhook logs). The captured request must include the full URL with query parameters and the valid Plivo V3 HMAC signature.
2. Analyze the webhook URL: Identify all query parameters in the captured webhook URL (e.g., ?CallUUID=abc&From=123&To=456).
3. Reorder query parameters: Construct a new request URL with the same query parameters in a different order (e.g., ?To=456&From=123&CallUUID=abc). The Plivo V3 signature remains valid because OpenClaw's signature verification sorts parameters before computing the HMAC.
4. Submit the replayed webhook: Send the modified request to the OpenClaw webhook endpoint. The replay cache will compute a hash of the raw (unsorted) URL, producing a different cache key than the original request, and will not detect it as a duplicate.
5. Trigger duplicate processing: OpenClaw processes the replayed webhook as a new event, executing the associated voice-call business logic again. Repeat with additional parameter permutations to trigger further duplicate processing (GitHub Advisory).

• Logs: Multiple webhook processing log entries for the same CallUUID or equivalent voice-call identifier within a short time window, with slightly different raw request URLs (differing only in query parameter order).
• Network: Repeated inbound HTTP POST requests to the OpenClaw Plivo V3 webhook endpoint from the same or different source IPs, carrying identical Plivo signature headers but with query parameters in different orderings.
• Application Behavior: Unexpected duplicate voice-call events, repeated billing triggers, or duplicated call-handling actions in the OpenClaw application that do not correspond to legitimate Plivo platform activity.

Upgrade OpenClaw to version 2026.3.28 or later, which fixes the issue by canonicalizing (sorting) query parameters before computing the replay cache key, ensuring consistency with the signature verification step (commit 85777e726c) (GitHub Advisory). No official configuration-based workaround is documented; upgrading is the recommended and only confirmed remediation. As an interim measure, operators should review webhook processing logs for duplicate voice-call events that may indicate exploitation attempts.