CVE-2026-55552 Details.
Yamcs <=5.11.12 - Arbitrary File Read
Atlas does not check this one. Needs a scripted sequence.
This check is a series of requests where each step depends on the last, often after logging in. Atlas runs single, read-only probes, so it does not run this one.
About CVE-2026-55552. What It Means.
Yamcs through 5.11.12 serves static web resources through a handler that resolves the requested path against the configured web root without rejecting absolute paths. A request path that begins with a double slash is resolved as an absolute filesystem path, discarding the web root, and the handler returns the referenced file from the underlying host, letting unauthenticated attackers read any non-hidden file readable by the Yamcs service account whose path contains no dot se…
Affected Product. What Is Hit.
- Vendor
- yamcs
- Product
- Yamcs
References. Where To Read More.
- https://github.com/yamcs/yamcs/security/advisories/GHSA-9jg3-g3wh-w9pj
- https://github.com/yamcs/yamcs/commit/f4bc588880c166849e983aa8f65b9c8107d06091
- https://github.com/yamcs/yamcs/commit/c7dfd24e469ae1086c23e0fe04401cb1ce4260d4
- https://github.com/yamcs/yamcs/releases/tag/yamcs-5.11.13
- https://nvd.nist.gov/vuln/detail/CVE-2026-55552
FAQ
Common Questions.
Yamcs <=5.11.12 - Arbitrary File Read. Yamcs through 5.11.12 serves static web resources through a handler that resolves the requested path against the configured web root without rejecting absolute paths. A request path that begins with a double slash is resolved as an absolute filesystem path, discarding the web root, and the handler returns the referenced file from the underlying host, letting unauthenticated attackers read any non-hidden file readable by the Yamcs service account whose path contains no dot se…
No. This check is a series of requests where each step depends on the last, often after logging in. Atlas runs single, read-only probes, so it does not run this one. The facts about CVE-2026-55552 are on this page, and you can request a demo to see how Brandefense watches your whole external attack surface.
CVE-2026-55552 is not on the CISA Known Exploited Vulnerabilities list at the time of writing, but it is still worth fixing.
Update Yamcs to the latest version from the vendor, or follow the vendor's advice to switch off the affected feature. Vendor links are listed on this page when they are known.
This page lists the public facts about CVE-2026-55552. Atlas does not run a check for it, so nothing here says whether a particular site is affected.