CVE-2026-49837

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    CVE-2026-49837

    Published: 10 Sept 2026Last Modified: 12 Sept 2026

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

    Details: 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.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49837.json, https://github.com/osrg/gobgp/security/advisories/GHSA-gjrg-jjr3-56cm, https://nvd.nist.gov/vuln/detail/CVE-2026-49837, https://github.com/osrg/gobgp/commit/f02ca397821f6ca182ef4eb492c3cbc459552d7c

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -f02ca397821f6ca182ef4eb492c3cbc459552d7c

    Affected versions

    v4.5.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-49837 | CVE-DB