- CVE-2026-100555 affects OpenClaw versions from 2026.7.1 up to, but not including, 2026.8.1. The Gateway checked a file URL's address, then handed the NAS the hostname to look up again.
- This matters because a check only protects you if the checked result is the one used. The NVD record carries a 7.1 (High) score from VulnCheck.
- Upgrade to 2026.8.1, or turn off remote URL attachment forwarding in Synology Chat. Then audit where your own systems check a hostname and pass it on.
A security check is only as good as the moment it covers. If a system checks one thing and then acts on another, the check has protected nothing. CVE-2026-100555, an OpenClaw flaw published in the NIST National Vulnerability Database (NVD), is a clean example of that gap.
What the NVD record says
OpenClaw is an npm-distributed gateway application. The record covers versions from 2026.7.1 up to, but not including, 2026.8.1. The problem sits in Synology Chat attachment delivery.
When a user supplies a file URL, the OpenClaw Gateway checks where its hostname points. It validates a single DNS result. It then passes the original hostname, not the checked address, on to the Synology NAS. The NAS looks the name up again, and the answer can differ.
How the trick works
DNS is the system that turns a name like example.com into a numeric address. Each lookup is a fresh question. A name can answer differently the second time. Attackers who control a name can exploit that. The technique is called DNS rebinding.
Here, the first answer points somewhere harmless, so the Gateway's check passes. The second answer, given to the NAS, points somewhere else. NVD describes the result as server-side request forgery (SSRF). The NAS fetches a private or otherwise policy-denied resource. It then returns the contents to the addressed conversation.
The defence is called DNS pinning. The checked address is locked in and reused for the actual request. The record says this pinning was lost when the hostname was handed to the NAS. Security engineers know the general pattern as time-of-check to time-of-use. The check and the use were two separate lookups.
What limits the risk
The record is careful on this point. An attacker needs attachment delivery to accept a hostname that someone outside can influence. NVD adds that real-world impact will vary. Three things shape it: how the NAS routes traffic, how its resolver behaves, and what the private target actually returns.
The score reflects this. VulnCheck, which scored the flaw, rates it 7.1 (High) under both CVSS 3.1 and CVSS 4.0. The vector marks attack complexity as high and privileges required as low. It rates confidentiality impact as high and integrity impact as low.
The record does not say whether anyone has exploited this flaw. It also does not say how many deployments use Synology Chat attachment delivery.
Who carries the risk
The exposed party is whoever runs the gateway and a NAS that can reach internal resources. The NAS is the machine making the forged request. It may sit closer to private systems than the person typing in the chat. The attacker borrows that position.
The lesson here is about handoffs. When one component validates input and another component acts on it, the safe design passes along the validated result, not the original name. Every integration between two products is a place where that can break.
What to do
NVD lists 2026.8.1 as the fixed version. If you cannot upgrade yet, the record suggests a stopgap: switch off the Synology Chat feature that forwards attachments from remote URLs. The record points to a GitHub advisory (GHSA-cf95-m4jv-59rc) and a VulnCheck advisory for more detail.
Leaders can put four questions to their teams:
First, do we run OpenClaw between 2026.7.1 and 2026.8.1, and do we use Synology Chat attachments? Second, can the NAS reach internal systems that should be off limits? Third, who owns the upgrade or the workaround, and by when? Fourth, where else do our own tools check a hostname and then pass the name, not the address, to another system?
A check that cannot follow the request to where the work happens is a formality. Ask your team to prove the check and the action use the same answer.
Produced by the WebPulse Newsroom with AI assistance from the original reporting credited below, and checked against that source by our editorial review. How we use AI.
Original reporting: NIST NVD.
