CVE-2025-69250 Overview
CVE-2025-69250 is an information disclosure vulnerability affecting free5gc UDM (Unified Data Management), a component of the free5GC open-source 5th generation (5G) mobile core network project. The vulnerability exists in versions up to and including 1.4.1, where the service leaks detailed internal error messages to remote clients when processing invalid pduSessionId inputs. This exposes implementation details such as strconv.ParseInt parsing errors that can be leveraged for service fingerprinting and reconnaissance.
Critical Impact
Attackers can remotely fingerprint free5GC UDM deployments by triggering verbose error responses, potentially enabling targeted attacks against 5G mobile core network infrastructure.
Affected Products
- free5gc UDM versions up to and including 1.4.1
- All deployments using the UDM Nudm_UECM DELETE service
Discovery Timeline
- 2026-02-24 - CVE-2025-69250 published to NVD
- 2026-02-25 - Last updated in NVD database
Technical Details for CVE-2025-69250
Vulnerability Analysis
This vulnerability falls under CWE-20 (Improper Input Validation) and represents an error message information disclosure flaw. The free5GC UDM service fails to properly sanitize error responses when handling malformed pduSessionId inputs through the Nudm_UECM DELETE endpoint. When an attacker sends requests with invalid session identifiers, the service returns verbose error messages containing Go language-specific parsing errors like strconv.ParseInt failures, revealing implementation details about the underlying technology stack.
The network-accessible nature of this vulnerability means attackers can probe the service remotely without authentication. While the direct impact is limited to information disclosure rather than code execution, the exposed implementation details provide valuable reconnaissance data for adversaries seeking to identify and target free5GC deployments within 5G infrastructure.
Root Cause
The root cause is improper input validation in the UDM component's request processing logic. When the service receives an invalid pduSessionId parameter, it fails to catch parsing exceptions at the application layer and instead propagates raw Go runtime errors directly to the HTTP response. The vulnerable code path does not implement proper error handling boundaries that would sanitize or generalize error messages before returning them to clients.
Attack Vector
An attacker can exploit this vulnerability by sending crafted HTTP DELETE requests to the Nudm_UECM service endpoint with intentionally malformed pduSessionId values. The attack requires network access to the UDM service but does not require authentication or user interaction. By analyzing the detailed error responses, attackers can:
- Confirm the target is running free5GC UDM
- Identify the programming language and parsing libraries in use
- Gather implementation details useful for developing targeted exploits
- Enumerate potential input validation weaknesses
The security patch updates the github.com/free5gc/util dependency to implement proper input validation:
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
Detection Methods for CVE-2025-69250
Indicators of Compromise
- HTTP responses from UDM service containing strconv.ParseInt error strings
- Error messages exposing Go runtime details in API responses
- Unusual patterns of DELETE requests to Nudm_UECM endpoints with invalid session IDs
- Repeated probing attempts from single sources with malformed parameters
Detection Strategies
- Monitor UDM service logs for patterns of parsing errors triggered by external requests
- Implement application-layer logging to capture requests that generate verbose error responses
- Deploy web application firewalls (WAF) rules to detect reconnaissance patterns against the UDM endpoint
- Use network intrusion detection systems to identify scanning activity targeting 5G core services
Monitoring Recommendations
- Enable detailed access logging for the Nudm_UECM DELETE endpoint
- Configure alerting for elevated rates of 4xx/5xx responses from the UDM service
- Implement rate limiting on API endpoints to slow down fingerprinting attempts
- Review UDM service logs periodically for signs of reconnaissance activity
How to Mitigate CVE-2025-69250
Immediate Actions Required
- Update free5gc UDM to a patched version incorporating pull request #76
- Review UDM service access controls and restrict network exposure where possible
- Audit existing logs for evidence of exploitation attempts
- Consider deploying an API gateway with error response filtering in front of UDM services
Patch Information
The fix is available through GitHub Pull Request #76, which has been merged into the repository. The patch updates the github.com/free5gc/util dependency from version v1.3.2-0.20260107090449-c09baaf75b11 to v1.3.2-0.20260204030658-79d56f347175. The specific commit containing the fix is 504b14458d156558b3c0ade7107b86b3d5e72998.
Additional resources:
Workarounds
- No direct application-level workaround is available according to the vendor advisory
- Implement network segmentation to limit access to the UDM service from untrusted networks
- Deploy a reverse proxy or API gateway that sanitizes error responses before returning them to clients
- Apply strict firewall rules to allow only trusted sources to communicate with the UDM service
# Example: Restrict UDM service access using iptables
# Allow only trusted network ranges to access UDM service port
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
