CVE-2026-59863: Kiota: Workspace-config poisoning: out-of-repo file write + generation-time SSRF
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 (KIOTACONFIGPREVIEW=true, the self-contained linux-x64 release binary).
Details
jsonc // .kiota/workspace.json (committed to the repo) "clients": { "MyClient": { "outputPath": "/abs/path/outside/repo/pwnedclient" // -> 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.
Impact
A malicious or compromised repository — or a malicious PR that edits .kiota/workspace.json — leads to arbitrary file write on the developer's or CI host's filesystem (overwrite source/build files, drop files in auto-loaded locations) whenever a teammate clones/pulls and runs the documented kiota client generate / kiota plugin generate to refresh the client. CWE-22.
This is a different trust boundary from the OpenAPI-description-based findings: the malicious input is the Kiota config, not the spec.
Patches
Fixed in 1.32.5 (https://github.com/microsoft/kiota/pull/7885). On loading a workspace configuration, each client/plugin outputPath is validated to be a relative subdirectory of the workspace: null/empty, rooted paths (POSIX /, UNC \\ / //, Windows drive X:\), and any .. traversal segment are rejected, and the resolved full path must stay under the workspace root. Generation aborts with an error if any consumer's outputPath escapes the workspace.
Remediation
Upgrade to Kiota 1.32.5 or later. Review any committed workspace configs for outputPath values that point outside the workspace.
Other sources
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.
— NVD
Kiota is an OpenAPI based HTTP Client code generator. Prior to 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 1.32.5.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
nuget/Microsoft.OpenApi.Kiota.Builderto a version that resolves this vulnerability.Fixed in 1.32.5 - Upgrade
Upgrade
nuget/Microsoft.OpenApi.Kiotato a version that resolves this vulnerability.Fixed in 1.32.5 - Upgrade
Upgrade
microsoft/kiotato a version that resolves this vulnerability.Fixed in 1.32.5 - Configuration
Review committed `.kiota/workspace.json` files and ensure each per-client/per-plugin `outputPath` used by `kiota client generate` / `kiota plugin generate` is validated to be a relative subdirectory of the workspace root. Reject absolute rooted POSIX paths ('/'), UNC paths ('\\' or '//'), Windows drive paths ('X:\'), and any '..' traversal segments that would escape the workspace root during generation-time writes.
Microsoft Kiota workspace configuration (.kiota/workspace.json) outputPath (per-client/per-plugin) = a relative subdirectory of the workspace root only (no null/empty; no absolute paths; no '..' traversal; no rooted POSIX '/', UNC '\' or '//' , no Windows drive 'X:\')
Event History
Frequently Asked Questions
What is the severity of CVE-2026-59863?
The severity of CVE-2026-59863 is classified as high with a CVSS score of 7.
What kind of vulnerability is CVE-2026-59863?
CVE-2026-59863 is a path traversal vulnerability affecting Kiota that can lead to workspace-config poisoning.
How does CVE-2026-59863 affect Kiota?
CVE-2026-59863 allows a malicious repository to manipulate the .kiota/workspace.json configuration, enabling file writes and possible SSRF at generation time.
How do I fix CVE-2026-59863?
To fix CVE-2026-59863, upgrade to Kiota version 1.32.5 or later where the vulnerability is addressed.
What should I do if I'm using an affected version of Kiota regarding CVE-2026-59863?
If you are using an affected version of Kiota, you should immediately update to the latest version to mitigate the risk of exploitation.