What’s Vulnerable › Vulnerabilities

CVE-2026-33192: free5GC UDM incorrectly returns 500 for empty supi path parameter in PATCH sdm-subscriptions reques

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-20 · updated 2026-06-17
• Weakness: CWE-209

Description

Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. In versions prior to 1.4.2, 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, making it difficult for clients to distinguish between client-side errors and server-side failures. The issue has been patched in version 1.4.2.

Affected products

• free5gc udm: before 1.4.2 — fixed in 1.4.2

How to fix

Upgrade to a fixed version: free5gc udm 1.4.2. Check the vendor advisory for mitigations.

References

• https://github.com/free5gc/free5gc/issues/784
• https://github.com/free5gc/free5gc/security/advisories/GHSA-5rvc-5cwx-g5x8
• https://github.com/free5gc/udm/pull/79

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