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🛡️ CVE-2026-33065 — udm

🟡 CVSS 5.3 — Medium ✅ No Known Exploit CWE-209 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

free5GC UDM incorrectly returns 500 for empty supi path parameter in DELETE sdm-subscriptions request

Impact

This is an Improper Error Handling vulnerability with Information Exposure implications.

  • Security Impact: The UDM incorrectly converts a downstream 400 Bad Request (from UDR) into a 500 Internal Server Error when handling DELETE requests with an empty supi path parameter. This leaks internal error handling behavior and makes it difficult for clients to distinguish between client-side errors and server-side failures.
  • Functional Impact: When a client sends a DELETE request with an empty supi (e.g., double slashes // in URL path), the UDM forwards the malformed request to UDR, 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 DELETE operations.
  • Affected Parties: All deployments of free5GC v4.0.1 using the UDM Nudm_SDM service with DELETE operations on sdm-subscriptions endpoint.

Patches

Yes, the issue has been patched.

The fix is implemented in PR free5gc/udm#79.

Users should upgrade to the next release of free5GC that includes this commit.

Workarounds

There is no direct workaround at the application level. The recommendation is to apply the provided patch or implement API gateway-level validation to reject DELETE requests with empty path parameters before they reach UDM.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-33065 is classified as CWE-209: Information Exposure Through an Error Message. Error output includes internal detail such as paths, queries or stack traces that assists an attacker.

Affected software

CVE-2026-33065 is recorded against 2 packages.

  • github.com/free5gc/udm
  • udm (fixed in 1.4.2)

Timeline and source

Published on 18 March 2026 and last revised on 23 March 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Web)
github.com (Package)

Other advisories for this package

github.com/free5gc/udm has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-209: Information Exposure Through an Error Message) in other software:

CVE-2026-33065 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE CWE-209
Public Exploit ✅ No
Source NVD
Published 2026-03-18
Updated 2026-08-20
Modified 2026-03-23

Affected Packages

Software From version Fixed in
github.com/free5gc/udm — —
udm — 1.4.2

Similar Threats

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