GoBGP: BGP OPEN capability parser may read capability values outside declared CapLen boundaries

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-49837
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-10 22:16:57 UTC
Updated2026-09-10 22:16:57 UTC
DescriptionGoBGP 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.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS: 0.002550000 probability, percentile 0.170980000 (date 2026-09-11)

Problem Types: CWE-125 | CWE-125 CWE-125: Out-of-bounds Read

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Osrg Gobgp affected < 4.6.0 Not specified

References

ReferenceSourceLinkTags
github.com/osrg/gobgp/commit/f02ca397821f6ca182ef4eb492c3cbc459552d7c [email protected] github.com
github.com/osrg/gobgp/security/advisories/GHSA-gjrg-jjr3-56cm [email protected] github.com
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