CVE-2026-34761 Overview
CVE-2026-34761 is a Null Pointer Dereference vulnerability affecting Ella Core, a 5G core network solution designed for private networks. Prior to version 1.8.0, the Ella Core software panics when processing malformed NGAP (NG Application Protocol) handover failure messages, allowing an attacker to crash the core network process and cause service disruption for all connected subscribers.
Critical Impact
An attacker who can influence a gNodeB (5G base station) to send crafted NGAP handover failure messages to Ella Core can crash the entire 5G core process, resulting in denial of service for all connected 5G subscribers on the private network.
Affected Products
- Ella Core versions prior to 1.8.0
- Private 5G network deployments using vulnerable Ella Core versions
- Systems processing NGAP handover failure messages from gNodeB connections
Discovery Timeline
- 2026-04-02 - CVE CVE-2026-34761 published to NVD
- 2026-04-02 - Last updated in NVD database
Technical Details for CVE-2026-34761
Vulnerability Analysis
This vulnerability is classified as CWE-476 (NULL Pointer Dereference), a memory corruption issue that occurs when the application attempts to use a pointer that has a NULL value. In the context of Ella Core, the vulnerability manifests during the processing of NGAP handover failure messages received from gNodeB devices.
The NGAP protocol is a critical component of 5G network architecture, facilitating communication between the Radio Access Network (RAN) and the 5G Core (5GC). Handover failure messages are sent when a mobile device fails to complete a handover between cells. When Ella Core receives a malformed or unexpected handover failure message, the application fails to properly validate the message contents before dereferencing pointers, leading to a panic condition that crashes the entire core network process.
The attack requires network access and high privileges (the ability to control or compromise a gNodeB), combined with high attack complexity. However, the scope is changed (S:C) because a successful attack impacts all subscribers connected to the 5G core, not just the immediate target.
Root Cause
The root cause is improper input validation in the NGAP message handler. When processing handover failure messages, the code fails to check for null or missing fields before attempting to access them. This causes a null pointer dereference that triggers a panic in the Go runtime, immediately terminating the Ella Core process.
Attack Vector
The attack is network-based and requires an attacker to either compromise a legitimate gNodeB or position a rogue gNodeB that can communicate with the Ella Core instance. The attacker must craft NGAP handover failure messages with missing or malformed fields that trigger the null pointer dereference condition.
The vulnerability exists in the NGAP message processing pipeline where handover failure messages are parsed and handled. When certain expected fields are absent or contain null values, the handler code attempts to access these fields without proper null checks, causing the Go runtime to panic and terminate the process.
For technical details on the specific vulnerable code paths and the patch implementation, refer to the GitHub Security Advisory GHSA-6gm8-3g4h-w82m.
Detection Methods for CVE-2026-34761
Indicators of Compromise
- Unexpected Ella Core process termination or restart events
- Panic messages in Ella Core logs referencing NGAP handover failure processing
- Unusual patterns of handover failure messages from specific gNodeBs
- Service disruption affecting multiple subscribers simultaneously
Detection Strategies
- Monitor Ella Core process stability and implement alerts for unexpected crashes or restarts
- Implement deep packet inspection on NGAP traffic to detect malformed handover failure messages
- Deploy anomaly detection on gNodeB communication patterns to identify compromised or rogue base stations
- Enable verbose logging for NGAP message processing to capture pre-crash diagnostic information
Monitoring Recommendations
- Implement process health monitoring with automatic alerting for Ella Core crashes
- Log and analyze all NGAP handover failure messages for malformed content or unusual patterns
- Monitor network traffic between gNodeBs and the 5G core for volumetric anomalies
- Establish baseline metrics for normal handover failure rates to detect attack patterns
How to Mitigate CVE-2026-34761
Immediate Actions Required
- Upgrade Ella Core to version 1.8.0 or later immediately
- Review network access controls to restrict which devices can send NGAP messages to the core
- Implement network segmentation to isolate the 5G core from untrusted network segments
- Enable process restart mechanisms to minimize downtime during potential exploitation attempts
Patch Information
The vulnerability has been patched in Ella Core version 1.8.0. The patch adds proper null pointer validation before processing NGAP handover failure message fields. Organizations should download the patched version from the GitHub Release v1.8.0.
Workarounds
- Implement network-level filtering to drop malformed NGAP messages before they reach Ella Core
- Deploy a reverse proxy or protocol gateway that validates NGAP message structure
- Restrict gNodeB connections to authenticated and trusted devices only
- Consider deploying Ella Core in a containerized environment with automatic restart policies to reduce downtime impact
# Example: Configure process restart policy for Ella Core
# systemd service configuration to auto-restart on crash
[Service]
Restart=always
RestartSec=5
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
