CVE-2026-40343 free5GC UDR: Fail-open handling in PolicyDataSubsToNotifyPost allows unintended subscription creation
Attackers can create unintended policy data subscriptions in free5GC UDR by exploiting fail-open error handling during request processing.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40343?
CVE-2026-40343 is a medium-severity vulnerability in Free5gc Free5gc, published on 21 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
free5GC UDR is the user data repository (UDR) for free5GC, an an open-source project for 5th generation (5G) mobile core networks. In versions up to and including 1.4.2, a fail-open request handling flaw in the UDR service causes the `/nudr-dr/v2/policy-data/subs-to-notify` POST handler to continue processing requests even after request body retrieval or deserialization errors. This may allow unintended creation of Policy Data notification subscriptions with invalid, empty, or partially processed input, depending on downstream processor behavior. As of time of publication, a patched version is not available.
Weakness: CWE-754
Which versions are affected by CVE-2026-40343?
3 open source packages ship an affected version, including github.com/free5gc/udr. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
github.com/free5gc/udr Go | All versions | None |
github.com/free5gc/udr Go | All versions to 1.4.2 | None |
github.com/free5gc/udr Go | All versions to 1.4.2 | None |
Products include Free5gc Free5gc, Free5gc Udr.
How do I fix CVE-2026-40343?
No fix published yet.
Is CVE-2026-40343 being exploited?
There is no known exploitation of CVE-2026-40343 in the wild and no public exploit code.
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-jwch-w7wh-gqjm, GO-2026-5482.