CVE-2026-42459 Free5GC UDM has Improper Input Validation and Generation of Error Messages Containing Sensitive Information
An unauthenticated attacker can inject control characters into the SUPI parameter to trigger errors that expose internal infrastructure details in free5GC UDM.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42459?
CVE-2026-42459 is a high-severity vulnerability in Free5gc Free5gc, published on 27 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the free5GC UDM component fails to validate the supi path parameter in six GET handlers of the nudm-sdm (Subscriber Data Management) service. An unauthenticated attacker can inject control characters into the SUPI parameter, causing UDM to forward a malformed request to UDR and return a 500 Internal Server Error response that exposes internal infrastructure details. This vulnerability is fixed in 4.2.2.
Which versions are affected by CVE-2026-42459?
3 open source packages ship an affected version, including github.com/free5gc/udm. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/free5gc/udm Go | All versions | None |
github.com/free5gc/udm Go | All versions to 1.4.3 | None |
github.com/free5gc/udm Go | All versions to 1.4.3 | None |
Products include Free5gc Free5gc.
How do I fix CVE-2026-42459?
Upgrade to a fixed version.
Is CVE-2026-42459 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42459 exists.
Other vulnerabilities in Free5gc Free5gc
- CVE-2026-44327 free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler
- CVE-2026-44329 free5GC's SMF UPI management interface lacks auth middleware; unauthenticated topology read/write requests reach handlers
- CVE-2026-44330 free5GC's NEF nnef-pfdmanagement API is unauthenticated; forged bearer tokens can read PFD data and create/delete PFD subscriptions
- CVE-2025-63679 Memory corruption in n/a
- CVE-2026-44315 free5GC's NEF 3gpp-pfd-management API is unauthenticated; forged bearer tokens can create, read, and delete PFD transactions
Sources
Also known as GHSA-585v-hcgf-jhfr, GO-2026-5138.