CVE-2025-69252 Overview
CVE-2025-69252 is a NULL Pointer Dereference vulnerability (CWE-476) affecting the Unified Data Management (UDM) component of free5GC, an open-source project implementing 5th generation (5G) mobile core networks. The vulnerability allows remote unauthenticated attackers to trigger a service panic (Denial of Service) by sending a crafted PUT request with an unexpected ueId parameter, causing the UDM service to crash.
Critical Impact
Remote unauthenticated attackers can crash the UDM service in free5GC deployments, disrupting 5G core network operations and potentially affecting subscriber data management services.
Affected Products
- free5gc UDM versions up to and including 1.4.1
- All deployments of free5GC using the UDM component
Discovery Timeline
- 2026-02-24 - CVE-2025-69252 published to NVD
- 2026-02-25 - Last updated in NVD database
Technical Details for CVE-2025-69252
Vulnerability Analysis
This vulnerability exists in the UDM (Unified Data Management) component of free5GC, which is responsible for managing subscriber data in 5G core networks. The flaw manifests when the UDM service processes PUT requests containing unexpected or malformed ueId values. When an attacker sends a specially crafted request with an invalid ueId, the application fails to properly validate the input before dereferencing a pointer, resulting in a NULL pointer dereference condition.
The vulnerability is particularly concerning in 5G network deployments because the UDM is a critical network function that handles subscriber authentication, authorization, and session management data. A successful exploit does not require authentication, making it accessible to any network-level attacker who can reach the UDM service endpoint.
Root Cause
The root cause is inadequate input validation in the UDM Context Management (UECM) handling logic. When processing PUT requests, the code fails to verify that the ueId parameter references a valid, initialized data structure before attempting to dereference it. This missing null check allows crafted requests to trigger a panic condition when the application attempts to access memory through an uninitialized or null pointer.
Attack Vector
The attack is network-based and requires no authentication or user interaction. An attacker with network access to the UDM service can exploit this vulnerability by:
- Identifying the UDM service endpoint in the target free5GC deployment
- Crafting a PUT request with a malformed or unexpected ueId parameter
- Sending the request to trigger the NULL pointer dereference
- The UDM service panics and crashes, resulting in denial of service
The fix was implemented by updating the github.com/free5gc/util dependency to include proper input validation checks:
require (
github.com/asaskevich/govalidator v0.0.0-20210307081110-f21760c49a8d
github.com/free5gc/openapi v1.2.3
- github.com/free5gc/util v1.3.2-0.20260107090449-c09baaf75b11
+ github.com/free5gc/util v1.3.2-0.20260204030658-79d56f347175
github.com/gin-gonic/gin v1.10.0
github.com/google/uuid v1.6.0
github.com/h2non/gock v1.2.0
Source: GitHub Commit 504b14458d
Detection Methods for CVE-2025-69252
Indicators of Compromise
- Unexpected UDM service restarts or crashes without apparent cause
- Log entries showing panic conditions related to null pointer dereference in the UDM component
- Anomalous PUT requests to UDM endpoints with malformed or unusual ueId parameters
- Service unavailability patterns affecting 5G subscriber data management functions
Detection Strategies
- Monitor UDM service logs for panic stack traces containing null pointer dereference errors
- Implement network intrusion detection rules to identify malformed PUT requests targeting UDM endpoints
- Deploy application-level monitoring to detect repeated service restarts or crash patterns
- Analyze HTTP request logs for PUT requests with unexpected ueId formats or values
Monitoring Recommendations
- Enable verbose logging on the UDM service to capture detailed request information
- Configure alerting for UDM service crashes or unexpected restarts
- Implement rate limiting on UDM API endpoints to slow potential exploitation attempts
- Monitor network traffic patterns for reconnaissance activity targeting 5G core services
How to Mitigate CVE-2025-69252
Immediate Actions Required
- Apply the official patch by merging Pull Request #76 or updating to a patched version
- Update the github.com/free5gc/util dependency to version v1.3.2-0.20260204030658-79d56f347175 or later
- Restrict network access to UDM service endpoints to trusted network segments only
- Implement a web application firewall or API gateway to filter malformed requests
Patch Information
The vulnerability has been addressed in Pull Request #76 in the free5gc/udm repository. The fix adds proper input validation checks for the ueId parameter in UECM request handling. Organizations should update their deployments by applying commit 504b14458d156558b3c0ade7107b86b3d5e72998 or pulling the latest version from the repository. Additional details are available in the GitHub Security Advisory GHSA-v8cv-qvf6-9rpm and GitHub Issue #752.
Workarounds
- No direct workaround is available at the application level; applying the official patch is recommended
- Implement network-level access controls to restrict access to the UDM service from untrusted sources
- Deploy a reverse proxy or API gateway with request validation to filter malformed ueId parameters
- Consider temporarily isolating the UDM component until the patch can be applied
# Update go.mod to use patched util dependency
go get github.com/free5gc/util@v1.3.2-0.20260204030658-79d56f347175
go mod tidy
go build
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
