{"id":"CVE-2026-33192","aliases":["GHSA-5rvc-5cwx-g5x8","GO-2026-4755"],"url":"https://o3.security/vulnerability/CVE-2026-33192","summary":"free5GC UDM incorrectly returns 500 for empty supi path parameter in PATCH sdm-subscriptions reques","details":"**Impact**  \nThis is an Improper Error Handling vulnerability with Information Exposure implications, combined with an HTTP Method Translation issue.  \n- **Security Impact**: The UDM incorrectly converts a downstream 400 Bad Request (from UDR) into a 500 Internal Server Error when handling PATCH requests with an empty `supi` path parameter. Additionally, the UDM incorrectly translates the PATCH method to PUT when forwarding to UDR, indicating a deeper architectural issue. This leaks internal error handling behavior and makes it difficult for clients to distinguish between client-side errors and server-side failures.  \n- **Functional Impact**: When a client sends a PATCH request with an empty `supi` (e.g., double slashes `//` in URL path), the UDM forwards a PUT request to UDR with the malformed path, which correctly returns 400. However, UDM propagates this as 500 SYSTEM_FAILURE instead of returning the appropriate 400 error to the client. This violates REST API best practices for PATCH operations and may indicate improper HTTP method handling.  \n- **Affected Parties**: All deployments of free5GC v4.0.1 using the UDM Nudm_SDM service with PATCH operations on sdm-subscriptions endpoint.\n\n**Patches**  \nYes, the issue has been patched.  \nThe fix is implemented in PR free5gc/udm#79.  \nUsers should upgrade to the next release of free5GC that includes this commit.\n\n**Workarounds**  \nThere is no direct workaround at the application level. The recommendation is to apply the provided patch or implement API gateway-level validation to reject PATCH requests with empty path parameters before they reach UDM.","published":"2026-03-20T08:09:07.459Z","modified":"2026-08-12T03:51:24.006785120Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/free5gc/udm","fixedVersion":"1.4.2"}],"fix":{"url":"https://github.com/free5gc/udm/pull/79","label":"free5gc/udm#79"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33192.json"},{"type":"ADVISORY","url":"https://github.com/free5gc/free5gc/security/advisories/GHSA-5rvc-5cwx-g5x8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33192"},{"type":"REPORT","url":"https://github.com/free5gc/free5gc/issues/784"},{"type":"FIX","url":"https://github.com/free5gc/udm/pull/79"},{"type":"PACKAGE","url":"https://github.com/free5gc/udm"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:24.006785120Z"}}