CVE-2026-33580: OpenClaw < 2026.3.28 - Brute Force Attack via Missing Rate Limiting on Webhook Shared Secret Authentication

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-31 · updated 2026-07-24
Weakness: CWE-307

Description

OpenClaw before 2026.3.28 contains a missing rate limiting vulnerability in the Nextcloud Talk webhook authentication that allows attackers to brute-force weak shared secrets. Attackers who can reach the webhook endpoint can exploit this to forge inbound webhook events by repeatedly attempting authentication without throttling.

Affected products

OpenClaw: before 2026.3.28 — fixed in 2026.3.28

How to fix

Upgrade to a fixed version: OpenClaw 2026.3.28. Check the vendor advisory for mitigations.

References

https://github.com/openclaw/openclaw/commit/e403decb6e20091b5402780a7ccd2085f98aa3cd
https://github.com/openclaw/openclaw/security/advisories/GHSA-9528-x887-j2fp
https://www.vulncheck.com/advisories/openclaw-brute-force-attack-via-missing-rate-limiting-on-webhook-shared-secret-authentication

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