# CVE-2026-5124: osrg GoBGP BGP Header bgp.go BGPHeader.DecodeFromBytes access control

> Remote attackers can bypass access controls in GoBGP's BGP header decoding, requiring high complexity and difficult exploitation.

- **Severity:** Medium 6.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Mar 2026
- **Updated:** 30 Mar 2026
- **Also known as:** DEBIAN-CVE-2026-5124, GHSA-688c-h9c2-ffwg, UBUNTU-CVE-2026-5124

## What is CVE-2026-5124?

CVE-2026-5124 is a medium-severity missing authorization vulnerability in osrg GoBGP, published on 30 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A security vulnerability has been detected in osrg GoBGP up to 4.3.0. Affected is the function BGPHeader.DecodeFromBytes of the file pkg/packet/bgp/bgp.go of the component BGP Header Handler. The manipulation leads to improper access controls. Remote exploitation of the attack is possible. The attack is considered to have high complexity. The exploitability is told to be difficult. The identifier of the patch is f0f24a2a901cbf159260698211ab15c583ced131. To fix this issue, it is recommended to deploy a patch.

Weakness: CWE-284 (Improper Access Control), CWE-266 (Incorrect Privilege Assignment)

## Which versions are affected by CVE-2026-5124?

It affects 1 product.


Products: Osrg Gobgp.

## How do I fix CVE-2026-5124?

Apply the vendor's patch.

## Is CVE-2026-5124 being exploited?

There is no known exploitation of CVE-2026-5124 in the wild and no public exploit code.

## Other vulnerabilities in osrg GoBGP

- [CVE-2025-43971](https://insights.sbomify.com/CVE-2025-43971/): GoBGP panics due to a zero value for softwareVersionLen (high 8.6)
- [CVE-2026-41642](https://insights.sbomify.com/CVE-2026-41642/): GoBGP: Remote Denial of Service (Panic) via Malformed Well-known Path Attribute (high 7.5)
- [CVE-2026-41643](https://insights.sbomify.com/CVE-2026-41643/): GoBGP: Remote Denial of Service (Panic) in UpdatePathAttrs4ByteAs via Malformed BGP UPDATE (high 7.5)
- [CVE-2026-42285](https://insights.sbomify.com/CVE-2026-42285/): GoBGP: Panic in AdjRib.Update via malformed BGP Update message (Nil Pointer Dereference) (high 7.5)
- [CVE-2026-37461](https://insights.sbomify.com/CVE-2026-37461/): GoBGP has an out-of-bounds read in the ParseIP6Extended function (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5124 and fix it if it is affected.

What it is: CVE-2026-5124 is a medium-severity missing authorization vulnerability in osrg GoBGP, published on 30 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5124 in the wild and no public exploit code.

Affected product: osrg GoBGP. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5124/ (Markdown: https://insights.sbomify.com/CVE-2026-5124/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5124
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5124
- OSV: https://osv.dev/vulnerability/CVE-2026-5124

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5124/
Summaries are generated and may contain mistakes; the official description above is the record.