DeepWiki-Open EUVD-2026-55239

Exploitation requires network reachability to the DeepWiki-Open API server (api/api.py) and that the vulnerable wiki-cache and directory-creation endpoints are exposed without an authenticating proxy - both are described as unauthenticated, matching PR:N. The concrete trigger is supplying traversal payloads in the user-controlled owner, repo, and repo_type fields of the wiki-cache request, combined with the second endpoint's directory creation, so both primitives must be reachable to achieve reliable arbitrary write/delete. Impact severity is amplified because the process runs as root; if an operator has already dropped privileges or fronted the API with authentication/network ACLs, the practical impact and reachability are correspondingly reduced. No user interaction and no special client-side configuration are needed against a default root-running deployment.

The signals are largely aligned toward high real-world severity for exposed instances: CVSS 3.1 base 9.8 with AV:N/AC:L/PR:N/UI:N means remote, low-complexity, unauthenticated exploitation, and the described primitive (arbitrary write/delete as root) supports the I:H/A:H claim and plausibly C:H via write-to-RCE escalation. Tempering factors: no EPSS score, KEV entry, or POC was provided, so exploitation is currently theoretical/unproven rather than observed - treat the 9.8 as capability-based, not evidence of active campaigns. The dominant limiter is exposure and footprint: DeepWiki-Open is a niche self-hosted project, so aggregate internet exposure is far lower than for mainstream web servers, making this a high priority for the specific teams running it and a low aggregate-fleet concern otherwise. Note a minor tension: the raw vulnerability is a write/delete primitive (integrity/availability), so C:H rests on the reasonable but not stated inference that root file write yields code execution - verify before treating confidentiality loss as confirmed.

An attacker who can reach the DeepWiki-Open API sends a crafted wiki-cache request with owner/repo/repo_type values containing directory-traversal sequences, then uses the unauthenticated directory-creation endpoint to prepare the target path, causing the root-run service to write or delete a file outside the cache directory. By overwriting a root-writable file such as an SSH authorized_keys file, a cron job, or a startup script, the attacker escalates to remote code execution or, alternatively, deletes critical files to deny service. No public exploit code was identified, but AV:N/AC:L/PR:N/UI:N makes weaponization straightforward once the endpoint parameters are understood.