OpenCSG CSGHub CVE-2026-120426

No special conditions beyond reachability - remote, unauthenticated exploitation against default configurations of OpenCSG CSGHub up to and including v2.6.0-ce, via the public (unauthenticated) file resolve route. The specific trigger is injecting a percent-encoded current_user parameter into the requested file path, which the portal forwards to the backend server API using its own server API key, causing the authorization check to be bypassed. Limiting factors: the target must be a reachable CSGHub portal instance and the attacker must know or enumerate the path of a private model, code, or space repository; impact is confined to reading files (confidentiality only - no write or availability effect). No fixed version is identified in the available sources, so the primary limiting factor on remediation is the absence of a confirmed patched build in the evidence.

This is an unauthenticated information-disclosure flaw (CWE-639, IDOR / authorization bypass through a user-controlled key) in OpenCSG CSGHub's file resolve route. The supplied CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N) is internally consistent with the description: fully remote, low complexity, no privileges, no user interaction, with high confidentiality impact and no integrity or availability impact - a clean read-only exposure of private repository contents. The signals mostly agree: VulnCheck has published an advisory and there is a public HackMD technical write-up, and the vuln.today decision label is 'this_week', which places it as a near-term priority rather than an emergency. However, several escalation signals are ABSENT from the input: there is no EPSS probability provided, no CISA KEV listing, and no confirmation of weaponized exploit code - so active, widespread exploitation cannot be asserted. Net assessment: a genuinely exploitable, low-friction confidentiality bug that merits prompt patching given its trivial attack preconditions, but its real-world priority is tempered by the product's limited deployment footprint and the absence of KEV/EPSS data confirming mass exploitation. The 8.7 input score reflects ease of attack and high confidentiality loss; it is not inflated, but neither is there evidence of in-the-wild abuse.

A remote attacker with no account browses a CSGHub instance and targets a private model, code, or space repository. They craft a file-resolve request injecting a percent-encoded current_user parameter into the file path; the portal forwards the request to its server API using its own privileged server API key, bypassing the per-user authorization check and returning the private file contents. A public PoC reference (HackMD write-up and VulnCheck advisory) describes the technique, but it is not verified as working exploit code.