# CVE-2026-59859: Microsoft Kiota PHP code injection in generated string literals

Source: https://junglewise.ai/threats/cve-2026-59859-microsoft-kiota-php-code-injection-in-generated-string-literals  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-16. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-59859 · Severity: high · CVSS 4 · Published 2026-07-16

Microsoft Kiota is a tool used by developers to automatically generate API client code. A vulnerability in its PHP code generator allows an attacker to inject malicious code into the generated files by providing a specially crafted API specification. If a developer uses an untrusted specification to generate their client, the resulting code could allow an attacker to execute arbitrary commands on the server where the application is deployed.

Technologies: [Microsoft Kiota](https://junglewise.ai/threats/technologies/kiota), [Microsoft.OpenApi.Kiota](https://junglewise.ai/threats/technologies/microsoft-openapi-kiota), [Microsoft.OpenApi.Kiota.Builder](https://junglewise.ai/threats/technologies/microsoft-openapi-kiota-builder), [Microsoft.OpenApi.Kiota (NuGet)](https://junglewise.ai/threats/technologies/nuget-microsoft-openapi-kiota), [Microsoft.OpenApi.Kiota.Builder (NuGet)](https://junglewise.ai/threats/technologies/nuget-microsoft-openapi-kiota-builder). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft), [NuGet](https://junglewise.ai/threats/vendors/nuget).

## Quick answers

**Is CVE-2026-59859 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59859 being exploited in the wild.

**How severe is CVE-2026-59859?** High severity, with a CVSS score of 4, published 16 July 2026.

**Which products and versions are affected?** Microsoft Kiota < 1.32.4; Microsoft.OpenApi.Kiota < 1.32.4; Microsoft.OpenApi.Kiota.Builder < 1.32.4; Microsoft.OpenApi.Kiota (NuGet) ECOSYSTEM:introduced=1.30.0,fixed=1.32.4; and 1 more.

**Is there a fix for CVE-2026-59859?** Yes. Microsoft.OpenApi.Kiota (NuGet): upgrade to 1.32.4 or later; Microsoft.OpenApi.Kiota.Builder (NuGet): upgrade to 1.32.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-59859 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-59859?** Check whether you run Microsoft Kiota, Microsoft.OpenApi.Kiota, Microsoft.OpenApi.Kiota.Builder or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Microsoft.OpenApi.Kiota (NuGet): upgrade to 1.32.4 or later

  ```sh
  dotnet add package Microsoft.OpenApi.Kiota --version 1.32.4
  ```

- Microsoft.OpenApi.Kiota.Builder (NuGet): upgrade to 1.32.4 or later

  ```sh
  dotnet add package Microsoft.OpenApi.Kiota.Builder --version 1.32.4
  ```


## Technical details

The vulnerability exists in the Kiota PHP generator's 'StringExtensions.cs' component, specifically within the 'SanitizeDoubleQuote()' function. The generator fails to escape the '$' character when embedding OpenAPI fields (such as descriptions or default values) into PHP double-quoted string literals. Because PHP evaluates variables and expressions within double-quoted strings at runtime (interpolation), an attacker-controlled OpenAPI specification can include constructs like '{$eval(...)}' that will be executed when the generated PHP code is run. This is a remote attack vector requiring the victim to generate code from a malicious or compromised OpenAPI spec. A fix is available in version 1.32.4.

## Affected products

- Microsoft Microsoft.OpenApi.Kiota < 1.32.4
- Microsoft Microsoft.OpenApi.Kiota.Builder < 1.32.4

## Identifiers

- CVE-2026-59859
- GHSA-jqwh-526h-c92j

## Timeline

- 2026-06-30: disclosed
- 2026-07-16: advisory: NVD publication
- 2026-07-24: patched: GitHub Advisory published/reviewed

## References

- [https://api.github.com/users/peombwa](https://api.github.com/users/peombwa)
- [https://github.com/peombwa](https://github.com/peombwa)
- [https://api.github.com/users/peombwa/gists%7B/gist_id%7D](https://api.github.com/users/peombwa/gists%7B/gist_id%7D)
- [https://api.github.com/users/peombwa/repos](https://api.github.com/users/peombwa/repos)
- [https://avatars.githubusercontent.com/u/7061532?v=4](https://avatars.githubusercontent.com/u/7061532?v=4)
- [https://api.github.com/users/peombwa/events%7B/privacy%7D](https://api.github.com/users/peombwa/events%7B/privacy%7D)

## Related threats

- [Microsoft Kiota documentation-comment injection in Java and PHP](https://junglewise.ai/threats/cve-2026-105796-kiota-is-an-openapi-based-http-client-code-generator-from-0-5-0)
- [Kiota: Unsafe oauth_card_path references in Kiota-generated API plugin manifests](https://junglewise.ai/threats/cve-2026-105795-kiota-is-an-openapi-based-http-client-code-generator-from-1-25-1)
- [Microsoft Kiota path traversal in plugin manifest via percent-encoding bypass](https://junglewise.ai/threats/cve-2026-73851-microsoft-kiota-path-traversal-in-plugin-manifest-via-percent)
- [Microsoft Kiota SSRF and File Inclusion via OpenAPI external references](https://junglewise.ai/threats/cve-2026-59867-microsoft-kiota-ssrf-and-file-inclusion-via-openapi-external)
- [Microsoft Kiota path traversal and code injection in OpenAPI generation](https://junglewise.ai/threats/cve-2026-59866-microsoft-kiota-path-traversal-and-code-injection-in-openapi)