CVE-2026-53859: OpenClaw < 2026.5.26 - Hostname Validation Bypass via Trailing-Dot Inconsistency

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-16 · updated 2026-06-17
Weakness: CWE-918

Description

OpenClaw before 2026.5.26 contains a hostname validation vulnerability allowing attackers to bypass blocklist comparisons using trailing-dot notation in model or workspace-derived URLs. Attackers can exploit inconsistent hostname checks to reach destinations that operators intended to block through hostname policies.

Affected products

OpenClaw: before 2026.5.26; 2026.5.26-beta1, 2026.5.26-beta2 — fixed in 2026.5.26

How to fix

Upgrade to a fixed version: OpenClaw 2026.5.26. Check the vendor advisory for mitigations.

References

https://github.com/openclaw/openclaw/security/advisories/GHSA-gxg4-2rrr-jhc7
https://www.vulncheck.com/advisories/openclaw-hostname-validation-bypass-via-trailing-dot-inconsistency

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