EUVD-2026-56237Severity by source
AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
Tenant authentication required (PR:L), no special complexity, scope changes as operator upstream credentials relay requests to arbitrary external endpoints with high confidentiality impact.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
Lifecycle Timeline
4DescriptionCVE.org
Sub2API is an AI API gateway platform designed to distribute and manage API quotas from AI product subscriptions. From 0.1.135, to 0.1.168, platform API keys issued to tenants are exchanged for upstream requests made with shared provider accounts (ChatGPT/Codex OAuth, OpenAI platform keys, or an operator-configured base URL) that belong to the operator, not to the caller. The POST /responses/*subpath wildcard routes spliced the client-supplied subpath into the upstream URL with no validation. This lets an authenticated tenant relay requests to arbitrary upstream endpoints using pooled account credentials via a path traversal. This vulnerability is fixed in 0.1.169.
AnalysisAI
Path traversal in Sub2API versions 0.1.135-0.1.168 allows authenticated tenants to relay API requests to arbitrary upstream endpoints using operator-owned provider credentials (ChatGPT/Codex OAuth tokens, OpenAI platform keys, or operator-configured base URLs). The POST /responses/*subpath wildcard route accepted client-controlled subpaths and concatenated them into upstream URLs without sanitization, enabling scope-changing abuse of pooled shared accounts. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a valid tenant API key issued by a Sub2API operator running versions 0.1.135-0.1.168 - unauthenticated exploitation is not possible (CVSS PR:L). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 8.5 score with S:C accurately reflects that exploitation escapes the Sub2API trust boundary: the attacker does not merely affect the gateway but uses operator-owned upstream provider credentials to reach external AI provider APIs. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An authenticated tenant on a Sub2API deployment running versions 0.1.135-0.1.168 sends a POST request to /v1/responses/../../arbitrary/upstream/endpoint using their issued tenant API key. The gateway, performing no subpath validation, constructs an upstream URL that resolves outside the intended AI provider response prefix and forwards the request using the operator's pooled credentials. … |
| Remediation | Upgrade to Sub2API v0.1.169, confirmed fixed in the tagged release at https://github.com/Wei-Shaw/sub2api/releases/tag/v0.1.169 and commit 017f6bbd5edffea0639ef3c84c0391161983f1f3. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Inventory all Sub2API deployments and identify instances running versions 0.1.135-0.1.168; prioritize any handling sensitive API operations. …
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Same weakness CWE-22 – Path Traversal
View allSame technique Path Traversal
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External POC / Exploit Code
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