CVE-2026-41351Network attack vector

Webhook replay bypass via noncanonical signature hashing

Published Apr 23, 2026 · Updated Apr 23, 2026

Replay protection bypass in OpenClaw before 2026.3.31 allows remote attackers to replay valid Telnyx webhooks by re-encoding signatures. The verifyTelnyxWebhook function hashes the original signature text into its replay key even though verification decodes Base64 and Base64URL forms to identical bytes. Exploitation requires a captured valid Telnyx request against an enabled, publicly reachable voice-call webhook; it bypasses replay rejection but does not forge a signature.

CVSS severity6.3
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Replay protection bypass in OpenClaw before 2026.3.31 allows remote attackers to replay valid Telnyx webhooks by re-encoding signatures. The verifyTelnyxWebhook function hashes the original signature text into its replay key even though verification decodes Base64 and Base64URL forms to identical bytes. Exploitation requires a captured valid Telnyx request against an enabled, publicly reachable voice-call webhook; it bypasses replay rejection but does not forge a signature.

The record

CVE
CVE-2026-41351
Published
Apr 23, 2026
Updated
Apr 23, 2026
Vendor
OpenClaw Foundation
Product
OpenClaw
Classifications
CWE-294, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2026.3.31

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenClaw Foundation · OpenClawversion=0 <2026.3.31

Published CVSS scores

6.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
5.3VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-294Authentication Bypass by Capture-replay
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo