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

> Remote attackers can bypass access controls in GoBGP's BGP OPEN message handler by manipulating domain name length, requiring high complexity.

- **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-2026-5122, GHSA-vj73-h4qp-97x2, UBUNTU-CVE-2026-5122

## What is CVE-2026-5122?

CVE-2026-5122 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 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.

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

## Which versions are affected by CVE-2026-5122?

It affects 1 product.


Products: Osrg Gobgp.

## How do I fix CVE-2026-5122?

Apply the vendor's patch.

## Is CVE-2026-5122 being exploited?

There is no known exploitation of CVE-2026-5122 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-2026-5122 and fix it if it is affected.

What it is: CVE-2026-5122 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-2026-5122 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-2026-5122/ (Markdown: https://insights.sbomify.com/CVE-2026-5122/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5122
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5122
- OSV: https://osv.dev/vulnerability/CVE-2026-5122

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5122/
Summaries are generated and may contain mistakes; the official description above is the record.