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CVE-2026-49837— GoBGP: BGP OPEN capability parser may read capability values outside declared CapLen boundaries

Quick assessment

Affected
osrg gobgp
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

GoBGP 是一个使用 Go 编程语言实现的开源边界网关协议（BGP）实现。在 4.6.0 之前的版本中，存在一个 BGP OPEN 报文能力（capability）解析问题：多个具体的能力解码器可能会从整个剩余的能力缓冲区中解析数据，而不是严格限制在声明的能力长度 所界定的切片范围内。一个格式错误的 BGP OPEN 报文可能导致紧随其后的能力中的字节被误读为当前能力的一部分。在安全性方面，最相关的场景是 4 字节 AS 号能力：当某个能力的 时，解析器可能会将下一个能力的字节读取为 4 字节的 AS 值。该解析

CVSS 5.9 · Medium
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I. Basic Information for CVE-2026-49837

Vulnerability Information
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Vulnerability Title
GoBGP: BGP OPEN capability parser may read capability values outside declared CapLen boundaries
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
osrg gobgp < 4.6.0 -

II. Public POCs for CVE-2026-49837

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III. Intelligence Information for CVE-2026-49837

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Patches & Fixes for CVE-2026-49837 (1)

Vendor Advisories for CVE-2026-49837 (1)

IV. Related Vulnerabilities

Same product: gobgp
Same vendor: osrg
Same weakness: CWE-125

V. Comments for CVE-2026-49837

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