CVE-2026-37462 in gobgp
Summary
by MITRE • 06/03/2026
An integer underflow in the BGPUpdate.DecodeFromBytes function (/bgp/bgp.go) of gobgp v4.3.0 allows attackers to cause a Denial of Service (DoS) via supplying a crafted BGP UPDATE message.
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Analysis
by VulDB Data Team • 06/03/2026
The vulnerability identified in gobgp version 4.3.0 represents a critical integer underflow condition within the BGPUpdate.DecodeFromBytes function located in the bgp/bgp.go file. This flaw occurs when the software processes incoming BGP UPDATE messages, specifically during the decoding phase where it fails to properly validate integer values before performing arithmetic operations. The integer underflow manifests when the software attempts to subtract a value from an unsigned integer that results in a negative value, causing the integer to wrap around to a large positive value due to unsigned integer overflow behavior. This condition creates a predictable failure state that can be exploited by malicious actors to disrupt normal network operations.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the BGP message parsing logic. When a crafted BGP UPDATE message contains malformed or specially constructed data fields, the DecodeFromBytes function performs calculations without proper bounds checking on integer values that should represent message lengths or field sizes. This allows attackers to manipulate the integer arithmetic in such a way that the result causes the program to enter an invalid state where memory allocation or processing loops become unstable. The vulnerability directly maps to CWE-191, which specifically addresses integer underflow conditions, and can be categorized under ATT&CK technique T1499.200 for network denial of service attacks targeting specific protocols.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the stability and reliability of BGP routing operations within the network infrastructure. When exploited successfully, the integer underflow causes the gobgp daemon to crash or enter an infinite loop, effectively preventing it from processing legitimate BGP messages and maintaining proper routing information. This disruption can cascade through the network as affected routers lose their ability to exchange routing updates, potentially causing widespread routing instability and service degradation across multiple network segments. The vulnerability affects any system running gobgp version 4.3.0 that accepts BGP UPDATE messages from external peers, making it particularly dangerous in production environments where BGP is actively used for route propagation.
Mitigation strategies for this vulnerability require immediate attention through software updates and implementation of defensive coding practices. The primary solution involves upgrading to a patched version of gobgp that addresses the integer underflow condition through proper input validation and bounds checking. Additionally, network administrators should implement BGP message filtering and validation mechanisms at network boundaries to prevent malformed UPDATE messages from reaching vulnerable systems. The implementation of rate limiting and message size restrictions can serve as additional defensive measures to reduce the attack surface. Organizations should also consider deploying monitoring solutions that can detect unusual patterns in BGP message processing that may indicate exploitation attempts. Security teams should review their incident response procedures to ensure rapid detection and remediation capabilities for such protocol-level vulnerabilities that can compromise core network infrastructure components.