PatchSiren cyber security CVE debrief
CVE-2026-53859 OpenClaw CVE debrief
CVE-2026-53859 is a MEDIUM-severity vulnerability in OpenClaw, a software that contains a hostname validation vulnerability. This vulnerability allows attackers to bypass blocklist comparisons using trailing-dot notation in model or workspace-derived URLs. As a result, attackers can reach destinations that operators intended to block through hostname policies.
- Vendor
- OpenClaw
- Product
- Unknown
- CVSS
- MEDIUM 6
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-06-16
- Original CVE updated
- 2026-06-17
- Advisory published
- 2026-06-16
- Advisory updated
- 2026-06-17
Who should care
Users of OpenClaw before version 2026.5.26 should apply patches to prevent exploitation.
Technical summary
The vulnerability exists due to inconsistent hostname checks in OpenClaw. Specifically, the software does not properly handle trailing dots in URLs, allowing attackers to bypass blocklist comparisons. This can lead to unintended access to blocked destinations.
Defensive priority
MEDIUM
Recommended defensive actions
- Apply patches to update OpenClaw to version 2026.5.26 or later.
- Review and update hostname policies to account for trailing-dot notation.
Evidence notes
Evidence of this vulnerability can be found in the CVE record [cve-org] and the NVD detail page [nvd]. Additional information is available in the source references [ref-4] and [ref-5].
Official resources
CVE-2026-53859 was published on 2026-06-16T19:17:03.440Z and modified on 2026-06-16T20:42:46.200Z.