EUVD-2026-354318

fkie_cve-2026-59863

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.32.5, Kiota honored a poisoned .kiota/workspace.json workspace configuration without validating per-client or per-plugin outputPath values during kiota client generate and kiota plugin generate, allowing a malicious repository or pull request to use absolute paths, rooted POSIX / paths, UNC \\ or // paths, Windows drive X:\ paths, or .. traversal segments to write generated client files outside the workspace root on a developer or CI host. This issue is fixed in version 1.29.1 and 1.32.5.

GHSA-4rj6-vrwv-wr8m — Microsoft Kiota Workspace-config poisoning: out-of-repo file write + generation-time SSRF

Affected: NuGet: Microsoft.OpenApi.Kiota, NuGet: Microsoft.OpenApi.Kiota.Builder

### Summary

Microsoft Kiota honors a poisoned `.kiota/workspace.json` — the workspace configuration that Kiota's documented team workflow has developers commit to their repository — **unvalidated** on `kiota client generate` / `kiota plugin generate`. A repository (or pull request) containing a malicious per-client / per-plugin `outputPath` causes Kiota, when a developer or CI runs the documented regenerate command, to **(CWE-22) write the entire generated client to an arbitrary path outside the workspace** — the `outputPath` was not confined to the workspace root and absolute paths were accepted.

Confirmed on Kiota **1.32.4** (`KIOTA_CONFIG_PREVIEW=true`, the self-contained `linux-x64` release binary).

### Details

```jsonc // .kiota/workspace.json (committed to the repo) "clients": { "MyClient": { "outputPath": "/abs/path/outside/repo/pwned_client" // -> generated client written here (CWE-22) }} ```

Running `kiota client generate --client-name MyClient` in the repo writes `MyClient.cs`, `P/PRequestBuilder.cs`, … to the attacker-chosen `outputPath` (verified outside the working tree).

#### Note on `descriptionLocation`

The per-consumer `descriptionLocation` is intentionally fetched at generation time — this is how Kiota knows where to pull an updated description from when refreshing a client, the same way any other value in a committed lock/config file is honored. It is **not** treated as a vulnerability and is unchanged; only `outputPath` is now confined.

### I…

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EUVD-2026-354318

fkie_cve-2026-59863

GHSA-4rj6-vrwv-wr8m — Microsoft Kiota Workspace-config poisoning: out-of-repo file write + generation-time SSRF