# GHSA-rjwr-m7qx-3fjr: oapi-codegen: OpenAPI Server Description Escapes Generated Go Comment and Injects Executable Code

> Attackers can inject executable Go code via crafted OpenAPI server descriptions, requiring code review before execution.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 17 Jul 2026
- **Also known as:** GO-2026-6016

## What is GHSA-rjwr-m7qx-3fjr?

GHSA-rjwr-m7qx-3fjr is a code injection vulnerability in github.com/oapi-codegen/oapi-codegen, published on 17 Jul 2026. 

### Official description

## Summary

The vulnerability in oapi-codegen seems to be similar with CVE-2026-22785,  which is a generated-code injection issue where untrusted OpenAPI `summary` text is embedded into generated TypeScript MCP server source without proper escaping. `oapi-codegen` has a similar vulnerability in its server URL generator: untrusted OpenAPI `servers[].description` text is inserted into a generated Go line comment without normalizing embedded newlines. A crafted description can break out of the comment, add imports through `goimports`, and emit executable Go declarations into the generated package.

> [!NOTE]
> A vulnerability like this requires that it is missed in code review **and** that you then call the malicious method.
> 
> Using an `init()` function could be enough to not require a direct call to the code, and instead rely on you importing the package, but either way, code review should be performed before any `oapi-codegen` generated code is executed.
> 
> We **strongly recommend** all users to be reviewing changes to their generated code before they execute anything within it, to protect against supply chain attacks or malicious injected code.
>
> This is also why we recommend `oapi-codegen` generated code is committed to source control.

## Details
The vulnerable sink is in `pkg/codegen/templates/server-urls.tmpl`.

```gotemplate
// {{ .GoName }} defines the Server URL for {{ if len .OAPISchema.Description }}{{ .OAPISchema.Description }}{{ else }}{{ .OAPISchema.URL }}{{ end }}
const {{ .GoName}} = "{{ .OAPISchema.URL }}"
```

This template assumes the OpenAPI server description remains inside a single Go line comment. However, OpenAPI descriptions are attacker-controlled strings and may contain newlines. Once a newline is present, the next line is no longer part of the comment.

The same raw description is also used in the function form of server URL generation:

```gotemplate
// New{{ .GoName }} constructs the Server URL for {{ .OAPISchema.Description }}, with the provided variables.
func New{{ .GoName }}({{ .NewServerFunctionParams }}) (string, error) {
```

Identifier generation does not protect this sink. In `pkg/codegen/server_urls.go`, the description is normalized only for the generated Go identifier:

```go
suffix := server.Description
if suffix == "" {
	suffix = nameNormalizer(server.URL)
}
name = serverURLPrefix + UppercaseFirstCharacter(suffix)
name = nameNormalizer(name)
```

The identifier is sanitized, but the raw `server.Description` is still rendered in the comment template. This leaves the code-generation context vulnerable.

The generated file is then formatted with `goimports` in `pkg/codegen/codegen.go`:

```go
goCode := SanitizeCode(buf.String())

outBytes, err := imports.Process(opts.PackageName+".go", []byte(goCode), nil)
```

`SanitizeCode` only removes byte-order marks:

```go
func SanitizeCode(goCode string) string {
	return strings.ReplaceAll(goCode, "\uFEFF", "")
}
```

It does not escape comments, replace newlines, or otherwise serialize untrusted text for a Go source-code context. As a result, attacker-controlled source can be preserved and formatted as valid Go.

### How to Reproduce
The attacker-controlled input is an OpenAPI document whose `servers[].description` contains a newline followed by Go declarations:

```yaml
openapi: "3.0.0"
info:
  title: oapi-codegen server URL description injection
  version: "1.0.0"
servers:
  - url: https://api.example.com
    description: |
      benign
      var _ = func() int {
          panic("oapi-codegen generated-code execution")
          return 0
      }()
      //
paths: {}
```

Generate Go source with server URL generation enabled. No special local path or helper file is required for the vulnerability; the malicious description is copied into the generated source-code context.

The generated source contains attacker-controlled executable code:

```go
// ServerUrlBenignvarFuncIntPanicOapiCodegenGeneratedCodeExecutionReturn0 defines the Server URL for benign
var _ = func() int {
	panic("oapi-codegen generated-code execution")
	return 0
}()

//

const ServerUrlBenignvarFuncIntPanicOapiCodegenGeneratedCodeExecutionReturn0 = "https://api.example.com"
```

## Impact

An attacker who can supply or influence an OpenAPI document consumed by `oapi-codegen` can inject arbitrary Go source into the generated package. In common API-client/server generation workflows, this can lead to build-time or runtime code execution in developer machines, CI systems, or downstream applications that trust generated code.

## Which versions are affected by GHSA-rjwr-m7qx-3fjr?

4 open source packages ship an affected version, including github.com/oapi-codegen/oapi-codegen/v2 and github.com/oapi-codegen/oapi-codegen.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/oapi-codegen/oapi-codegen/v2` | Go | All versions | 2.7.1 |
| `github.com/oapi-codegen/oapi-codegen/v2` | Go | All versions | 2.7.1 |
| `github.com/oapi-codegen/oapi-codegen/v2` | Go | All versions | 2.7.1 |
| `github.com/oapi-codegen/oapi-codegen` | Go | All versions | None |

## How do I fix GHSA-rjwr-m7qx-3fjr?

Upgrade github.com/oapi-codegen/oapi-codegen/v2 to 2.7.1 or later.

## Is GHSA-rjwr-m7qx-3fjr being exploited?

There is no known exploitation of GHSA-rjwr-m7qx-3fjr in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-rjwr-m7qx-3fjr and fix it if it is affected.

What it is: GHSA-rjwr-m7qx-3fjr is a code injection vulnerability in github.com/oapi-codegen/oapi-codegen, published on 17 Jul 2026. 
Exploitation: There is no known exploitation of GHSA-rjwr-m7qx-3fjr in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/oapi-codegen/oapi-codegen/v2 (Go): affected all versions; fixed in 2.7.1
- github.com/oapi-codegen/oapi-codegen/v2 (Go): affected all versions; fixed in 2.7.1
- github.com/oapi-codegen/oapi-codegen/v2 (Go): affected all versions; fixed in 2.7.1
- github.com/oapi-codegen/oapi-codegen (Go): affected all versions; 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/GHSA-rjwr-m7qx-3fjr/ (Markdown: https://insights.sbomify.com/GHSA-rjwr-m7qx-3fjr/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-rjwr-m7qx-3fjr

---
From sbomify Insights: https://insights.sbomify.com/GHSA-rjwr-m7qx-3fjr/
Summaries are generated and may contain mistakes; the official description above is the record.