CVE-2025-15685 Overview
CVE-2025-15685 is a memory corruption vulnerability in Open5GS versions up to and including 2.7.1. The flaw resides in the freeDiameter component, which handles the Diameter protocol used for authentication, authorization, and accounting in 5G core networks. An attacker with low-privilege network access can trigger the memory corruption remotely, potentially impacting the availability and integrity of core network functions. Open5GS is widely deployed as an open source implementation of 5G Core and EPC, making the component a relevant attack surface for mobile network operators and research deployments. The weakness is tracked under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Critical Impact
Remote attackers with low privileges can corrupt memory in the freeDiameter subsystem of Open5GS, threatening the stability of 5G core signaling.
Affected Products
- Open5GS versions up to and including 2.7.1
- freeDiameter component within Open5GS
- Deployments of Open5GS-based 5G Core and EPC signaling nodes
Discovery Timeline
- 2026-08-12 - CVE-2025-15685 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2025-15685
Vulnerability Analysis
The vulnerability affects an unspecified function within the freeDiameter integration used by Open5GS. Processing of attacker-influenced Diameter protocol input results in memory corruption, classified under [CWE-119]. Diameter is the AAA signaling protocol used between core network elements such as the HSS, MME, and PCRF, so the affected code path is reachable over standard signaling interfaces. Exploitation requires network access and a low privilege level, with no user interaction. Impact is bounded to partial confidentiality, integrity, and availability loss on the vulnerable process. Successful triggering could destabilize signaling components and disrupt subscriber authentication or session management within the mobile core.
Root Cause
The root cause is improper enforcement of buffer boundaries during processing of Diameter messages inside the freeDiameter component. Memory operations on attacker-controlled input do not correctly validate size or offset, allowing corruption of adjacent memory. Full technical details are tracked in the upstream GitHub Issue #4156 and the VulDB entry for CVE-2025-15685.
Attack Vector
The attack is remote and requires only low privileges on the network path to a vulnerable Open5GS deployment. An attacker sends crafted Diameter signaling toward the exposed interface handled by freeDiameter. Processing of the malformed input triggers the memory corruption in the target process. No user interaction is needed to complete the attack.
A verified proof-of-concept has not been published. Refer to the Open5GS repository and the upstream issue tracker for authoritative technical detail.
Detection Methods for CVE-2025-15685
Indicators of Compromise
- Unexpected crashes, restarts, or segmentation faults in Open5GS processes that host the freeDiameter integration.
- Malformed or oversized Diameter AVPs (Attribute-Value Pairs) observed on signaling interfaces toward the affected component.
- Anomalous Diameter session establishment failures or authentication errors correlated with signaling from untrusted peers.
Detection Strategies
- Monitor process telemetry from Open5GS hosts for repeated crashes, core dumps, or abnormal memory growth in freeDiameter-backed services.
- Deploy protocol-aware inspection on Diameter traffic to identify malformed messages, invalid AVP lengths, and non-conforming command structures.
- Correlate signaling anomalies with source peer identity to detect low-privilege attackers abusing legitimate Diameter connections.
Monitoring Recommendations
- Enable verbose logging in Open5GS and forward logs to a central analytics platform for retention and correlation.
- Baseline normal Diameter peer behavior and alert on deviations in message rate, AVP composition, or session error ratios.
- Track availability metrics for HSS, MME, and PCRF equivalents to detect service disruption tied to signaling exploitation.
How to Mitigate CVE-2025-15685
Immediate Actions Required
- Inventory Open5GS deployments and identify any instances running version 2.7.1 or earlier.
- Restrict Diameter peer connectivity to trusted network elements using firewalling, IPsec, or dedicated signaling networks.
- Monitor the Open5GS GitHub repository and Issue #4156 for upstream fixes and apply updates as they become available.
Patch Information
At time of publication, no fixed version is referenced in the NVD entry. Track the upstream project for a release that supersedes Open5GS 2.7.1 and addresses the freeDiameter memory corruption. Vulnerability tracking data is available at VulDB Vulnerability #387278.
Workarounds
- Limit exposure of Diameter interfaces to authenticated, trusted peers only, and block signaling traffic from untrusted networks.
- Segment Open5GS signaling components onto isolated management networks with strict access control lists.
- Enable process supervision and automatic restart so that a crash of a freeDiameter-backed process does not cause prolonged outage while a patch is pending.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
