{"schema_version":"1.7.5","id":"GHSA-7g27-v5wj-jr75","published":"2026-03-18T20:06:36Z","modified":"2026-03-23T18:55:59.268001Z","aliases":["CVE-2026-33064","GO-2026-4757"],"summary":"free5GC UDM DataChangeNotification Procedure Panic Due to Nil Pointer Dereference","details":"**Impact**  \nThis is a NULL Pointer Dereference vulnerability leading to Denial of Service.  \n- **Security Impact**: A remote attacker can cause the UDM service to panic and crash by sending a crafted POST request to the `/sdm-subscriptions` endpoint with a malformed URL path containing path traversal sequences (`../`) and a large JSON payload. The `DataChangeNotificationProcedure` function in `notifier.go` attempts to access a nil pointer without proper validation, causing a complete service crash with \"runtime error: invalid memory address or nil pointer dereference\".  \n- **Functional Impact**: The service crashes completely, requiring manual restart. All UDM functionality is disrupted until recovery.  \n- **Affected Parties**: All deployments of free5GC v4.0.1 using the UDM HTTP callback functionality.\n\n**Patches**  \nYes, the issue has been patched.  \nThe fix is implemented in PR free5gc/udm#78.  \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 filtering to block requests containing path traversal sequences.","affected":[{"package":{"name":"github.com/free5gc/udm","ecosystem":"Go","purl":"pkg:golang/github.com/free5gc/udm"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.4.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-7g27-v5wj-jr75/GHSA-7g27-v5wj-jr75.json"}}],"references":[{"type":"WEB","url":"https://github.com/free5gc/free5gc/security/advisories/GHSA-7g27-v5wj-jr75"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33064"},{"type":"WEB","url":"https://github.com/free5gc/free5gc/issues/781"},{"type":"WEB","url":"https://github.com/free5gc/udm/pull/78"},{"type":"WEB","url":"https://github.com/free5gc/udm/commit/65d7070f4bfd016864cbbaefbd506bbc85d2fa92"},{"type":"PACKAGE","url":"https://github.com/free5gc/udm"}],"database_specific":{"cwe_ids":["CWE-476","CWE-478"],"github_reviewed":true,"github_reviewed_at":"2026-03-18T20:06:36Z","nvd_published_at":"2026-03-20T08:16:12Z","severity":"HIGH"},"severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}