CVE-2026-30405: GoBGP gobgpd DoS Vulnerability

CVE-2026-30405 Overview

A denial of service vulnerability exists in GoBGP gobgpd version 4.2.0 that allows a remote attacker to crash the BGP daemon through malicious manipulation of the NEXT_HOP path attribute. This vulnerability is classified as CWE-400 (Uncontrolled Resource Consumption), indicating that improper handling of specially crafted BGP UPDATE messages can lead to service disruption.

Critical Impact

Remote attackers can cause denial of service on GoBGP routing infrastructure by sending malformed NEXT_HOP path attributes, potentially disrupting network connectivity for dependent systems and services.

Affected Products

• GoBGP gobgpd v.4.2.0

Discovery Timeline

• 2026-03-16 - CVE CVE-2026-30405 published to NVD
• 2026-03-17 - Last updated in NVD database

Technical Details for CVE-2026-30405

Vulnerability Analysis

This denial of service vulnerability stems from improper input validation when processing the NEXT_HOP path attribute in BGP UPDATE messages. The NEXT_HOP attribute is a well-known mandatory attribute in BGP that specifies the IP address of the next-hop router along the path to the destination. When GoBGP gobgpd receives a specially crafted NEXT_HOP attribute, insufficient validation leads to uncontrolled resource consumption, ultimately causing the daemon to crash or become unresponsive.

The vulnerability is exploitable remotely over the network without requiring authentication or user interaction. An attacker with network access to the BGP daemon can send malicious BGP messages to trigger the denial of service condition. This is particularly concerning in routing infrastructure environments where BGP daemons maintain critical peering sessions.

Root Cause

The root cause is classified under CWE-400 (Uncontrolled Resource Consumption). The GoBGP daemon fails to properly validate or limit resource consumption when processing certain NEXT_HOP path attribute values. This allows an attacker to trigger conditions that exhaust system resources or cause unexpected program termination.

Attack Vector

The attack can be carried out remotely over the network by an unauthenticated attacker. The exploitation requires the attacker to have network connectivity to the target GoBGP instance, typically through an established BGP peering session or by exploiting open BGP ports. The attacker sends specially crafted BGP UPDATE messages containing malformed NEXT_HOP path attributes that trigger the vulnerability.

The attack does not require user interaction and has low complexity, making it relatively straightforward to exploit once an attacker has network access to the vulnerable service. The impact is limited to availability, with no confidentiality or integrity impact.

Detection Methods for CVE-2026-30405

Indicators of Compromise

• Unexpected crashes or restarts of the gobgpd process
• BGP session flaps or disconnections correlating with incoming UPDATE messages
• Log entries showing parsing errors related to NEXT_HOP path attributes
• Unusual BGP UPDATE messages from untrusted or newly established peers

Detection Strategies

• Monitor BGP daemon logs for parsing errors or crash events related to path attribute processing
• Implement network-level detection for malformed BGP UPDATE messages targeting NEXT_HOP attributes
• Deploy BGP session monitoring to detect unexpected session resets or daemon restarts
• Use SentinelOne Singularity to detect process crashes and anomalous behavior on routing infrastructure

Monitoring Recommendations

• Enable verbose logging on GoBGP instances to capture detailed BGP message processing information
• Implement alerting on gobgpd process termination or restart events
• Monitor system resource utilization (CPU, memory) on systems running GoBGP for abnormal consumption patterns
• Track BGP session stability metrics across peering relationships

How to Mitigate CVE-2026-30405

Immediate Actions Required

• Review the GitHub Issue Report for the latest information on patches and fixes
• Implement BGP MD5 authentication on all peering sessions to limit potential attackers to authenticated peers
• Apply network access controls to restrict BGP connectivity to only trusted and necessary peers
• Consider disabling or isolating vulnerable GoBGP v.4.2.0 instances until a patch is available

Patch Information

At the time of publication, users should monitor the GoBGP GitHub repository issue tracker for official patches and updated versions. Upgrading to a patched version when available is the recommended remediation approach.

Workarounds

• Implement strict BGP prefix filters and route policies to limit the scope of accepted BGP messages
• Use BGP TTL security (GTSM) to ensure BGP messages originate from directly connected peers
• Deploy intrusion detection/prevention systems capable of inspecting BGP traffic for malformed attributes
• Isolate routing infrastructure on dedicated network segments with strict access controls

# Example: Enable MD5 authentication for BGP peer (GoBGP configuration)
# Add authentication password for each peer to limit attack surface
[[neighbors]]
  [neighbors.config]
    neighbor-address = "192.0.2.1"
    peer-as = 65001
    auth-password = "strong_secret_password"