In short
- CVE-2026-33064 is a HIGH (CVSS 7.5) vulnerability affecting github.com/free5gc/udm, udm (free5gc).
- Chance of exploitation in the next 30 days (EPSS): 0.50%, higher than 42.5% of all vulnerabilities.
- Fix: update to 1.4.2 or later.
Description
Impact
This is a NULL Pointer Dereference vulnerability leading to Denial of Service.
- Security Impact: A remote attacker can cause the UDM service to panic and crash by sending a crafted POST request to the
/sdm-subscriptions endpoint with a malformed URL path containing path traversal sequences (../) and a large JSON payload. The DataChangeNotificationProcedure function in notifier.go attempts to access a nil pointer without proper validation, causing a complete service crash with "runtime error: invalid memory address or nil pointer dereference".
- Functional Impact: The service crashes completely, requiring manual restart. All UDM functionality is disrupted until recovery.
- Affected Parties: All deployments of free5GC v4.0.1 using the UDM HTTP callback functionality.
Patches
Yes, the issue has been patched.
The fix is implemented in PR free5gc/udm#78.
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 filtering to block requests containing path traversal sequences.
NVD description
Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. Versions prior to 1.4.2 are vulnerable to procedure panic caused by Nil Pointer Dereference in the /sdm-subscriptions endpoint. A remote attacker can cause the UDM service to panic and crash by sending a crafted POST request to the /sdm-subscriptions endpoint with a malformed URL path containing path traversal sequences (../) and a large JSON payload. The DataChangeNotificationProcedure function in notifier.go attempts to access a nil pointer without proper validation, causing a complete service crash with "runtime error: invalid memory address or nil pointer dereference". Exploitation would result in UDM functionality disruption until recovery by restart. This issue has been fixed in version 1.4.2.
More vulnerabilities in github.com/free5gc/udm
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