CVE-2026-5122Network attack vector

Peer domain corruption via ignored length field

Published Mar 30, 2026 · Updated Mar 30, 2026

BGP OPEN parsing flaw in GoBGP 4.0 through 4.3.0 allows remote attackers to append trailing data to a peer domain name. CapFQDN.DecodeFromBytes converts every byte after the host name into DomainName instead of stopping at the untrusted DomainNameLen value. Exploitation requires network access to the BGP service and a crafted FQDN capability; the demonstrated consequence is limited to parsed peer metadata.

CVSS severity6.3
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

BGP OPEN parsing flaw in GoBGP 4.0 through 4.3.0 allows remote attackers to append trailing data to a peer domain name. CapFQDN.DecodeFromBytes converts every byte after the host name into DomainName instead of stopping at the untrusted DomainNameLen value. Exploitation requires network access to the BGP service and a crafted FQDN capability; the demonstrated consequence is limited to parsed peer metadata.

The record

CVE
CVE-2026-5122
Published
Mar 30, 2026
Updated
Mar 30, 2026
Vendor
GoBGP
Product
GoBGP
Classifications
CWE-284, CWE-266
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.0
  2. Affected versionversion=4.1
  3. Affected versionversion=4.2
  4. Affected versionversion=4.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GoBGP · GoBGPversion=4.0; version=4.1; version=4.2; version=4.3.0

Published CVSS scores

1.9VulDBAV:N/AC:H/Au:N/C:N/I:P/A:N
3.7VulDBCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
6.3VulDBCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
CWE-266Incorrect Privilege Assignment

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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