GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. Versions prior to 4.6.0 contain a BGP OPEN capability parsing issue where several concrete capability decoders may parse data from the full remaining capability buffer instead of the slice bounded by the declared capability length, `CapLen`. A malformed BGP OPEN message can cause bytes from a following capability to be interpreted as part of the current capability. The most security-relevant case is the 4-octet AS capability, where a capability with `CapLen == 0` may cause the parser to read bytes from the following capability as the 4-octet AS value. This parsed value may later affect peer AS validation during BGP session establishment. Version 4.6.0 patches the issue.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-gjrg-jjr3-56cm GoBGP: BGP OPEN capability parser may read capability values outside declared CapLen boundaries
Fixes

Solution

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Workaround

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History

Thu, 10 Sep 2026 22:00:00 +0000

Type Values Removed Values Added
Description GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. Versions prior to 4.6.0 contain a BGP OPEN capability parsing issue where several concrete capability decoders may parse data from the full remaining capability buffer instead of the slice bounded by the declared capability length, `CapLen`. A malformed BGP OPEN message can cause bytes from a following capability to be interpreted as part of the current capability. The most security-relevant case is the 4-octet AS capability, where a capability with `CapLen == 0` may cause the parser to read bytes from the following capability as the 4-octet AS value. This parsed value may later affect peer AS validation during BGP session establishment. Version 4.6.0 patches the issue.
Title GoBGP: BGP OPEN capability parser may read capability values outside declared CapLen boundaries
Weaknesses CWE-125
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-10T21:56:13.637Z

Reserved: 2026-06-01T18:50:36.056Z

Link: CVE-2026-49837

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-10T22:16:57.507

Modified: 2026-09-10T22:16:57.507

Link: CVE-2026-49837

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses