CVE-2026-27642 free5GC has Improper Input Validation in UDM UEAU Service
Remote attackers can inject control characters into the UDM UEAU service to trigger errors that expose system details, aiding service fingerprinting.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-27642?
CVE-2026-27642 is a medium-severity vulnerability in free5gc udm, published on 24 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
free5gc UDM provides Unified Data Management (UDM) for free5GC, an open-source project for 5th generation (5G) mobile core networks. In versions up to and including 1.4.1, remote attackers can inject control characters (e.g., %00) into the supi parameter, triggering internal URL parsing errors (net/url: invalid control character). This exposes system-level error details and can be used for service fingerprinting. All deployments of free5GC using the UDM Nudm_UEAU service may be affected. free5gc/udm pull request 75 contains a fix for the issue. No direct workaround is available at the application level. Applying the official patch is recommended.
Weakness: CWE-20
Which versions are affected by CVE-2026-27642?
It affects 1 product.
Products include Free5gc Udm.
How do I fix CVE-2026-27642?
No fix has been published for CVE-2026-27642 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-27642 being exploited?
There is no known exploitation of CVE-2026-27642 in the wild and no public exploit code.
Other vulnerabilities in free5gc udm
- CVE-2026-33064 free5GC UDM DataChangeNotification Procedure Panic Due to Nil Pointer Dereference
- CVE-2026-33191 free5GC UDM vulnerable to null byte injection in URL path parameters causing 500 Internal Server Error
- CVE-2026-33192 free5GC UDM incorrectly returns 500 for empty supi path parameter in PATCH sdm-subscriptions reques
- CVE-2023-46324 free5GC udm vulnerable to Invalid Curve Attack
- CVE-2026-33065 free5GC UDM incorrectly returns 500 for empty supi path parameter in DELETE sdm-subscriptions request
Sources
Also known as GHSA-h4wg-rp7m-8xx4.