# CVE-2026-6993: go-kratos http.DefaultServeMux Fallback server.go NewServer confused deputy

> A confused deputy vulnerability in go-kratos allows remote attackers to bypass intended security controls via the HTTP server fallback handler.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Apr 2026
- **Updated:** 27 Apr 2026
- **Also known as:** GHSA-jj45-xvq5-rhh9, GO-2026-5471

## What is CVE-2026-6993?

CVE-2026-6993 is a medium-severity vulnerability in go-kratos kratos, published on 25 Apr 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 go-kratos kratos up to 2.9.2. This impacts the function NewServer of the file transport/http/server.go of the component http.DefaultServeMux Fallback Handler. The manipulation results in unintended intermediary. The attack may be launched remotely. The exploit has been released to the public and may be used for attacks. The patch is identified as 0284a5bcf92b5a7ee015300ce3051baf7ae4718d. Applying a patch is advised to resolve this issue.

Weakness: CWE-441 (Unintended Proxy or Intermediary)

## Which versions are affected by CVE-2026-6993?

3 open source packages ship an affected version, including github.com/go-kratos/kratos/v2.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/go-kratos/kratos/v2` | Go | All versions | None |
| `github.com/go-kratos/kratos/v2` | Go | All versions to 2.9.2 | None |
| `github.com/go-kratos/kratos/v2` | Go | All versions to 2.9.2 | None |

## How do I fix CVE-2026-6993?

Apply the vendor's patch.

## Is CVE-2026-6993 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6993 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6993 and fix it if it is affected.

What it is: CVE-2026-6993 is a medium-severity vulnerability in go-kratos kratos, published on 25 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6993 exists.

Affected packages and fixed versions:
- github.com/go-kratos/kratos/v2 (Go): affected all versions; no fix listed
- github.com/go-kratos/kratos/v2 (Go): affected all versions up to 2.9.2; no fix listed
- github.com/go-kratos/kratos/v2 (Go): affected all versions up to 2.9.2; no fix listed

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-2026-6993/ (Markdown: https://insights.sbomify.com/CVE-2026-6993/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6993
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6993
- OSV: https://osv.dev/vulnerability/CVE-2026-6993

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6993/
Summaries are generated and may contain mistakes; the official description above is the record.