CVE-2026-92812

decap-server, the npm-based local backend proxy used with Decap CMS (formerly Netlify CMS) local development workflows, enforces its repository-root containment with a plain string prefix comparison that does not validate path separators. As a result, paths pointing to sibling directories whose names merely begin with the repository directory's name (for example, 'myrepo' versus 'myrepo-backup') pass the containment guard and are treated as in-bounds. An attacker who can reach the proxy and satisfies the required conditions can read, write, or delete files in those sibling directories, with high confidentiality and integrity impact but no availability impact per the CVSS 4.0 vector (7.6, High; network vector, high complexity, no privileges). Anyone running decap-server is affected — typically developers or teams using the Decap CMS local_backend feature — with risk highest where the server is reachable beyond strict localhost or where sensitive directories share the repository's name prefix. No public proof-of-concept is known and the issue is not in CISA KEV, so no exploitation has been reported.

What to do: Upgrade decap-server as soon as a patched release is published, since no fixed version is identified in the advisory data. Until then, avoid running it on hosts containing sensitive sibling directories, keep it bound to localhost or behind a firewall/VPN, and audit for directories whose names share the repository name's prefix (e.g., 'myrepo' and 'myrepo-archive') adjacent to the served repository.