{"id":"CVE-2026-59863","aliases":["GHSA-4rj6-vrwv-wr8m"],"url":"https://o3.security/vulnerability/CVE-2026-59863","summary":"Kiota: Workspace-config poisoning: out-of-repo file write + generation-time SSRF","details":"### Summary\n\nMicrosoft Kiota honors a poisoned `.kiota/workspace.json` — the workspace configuration that Kiota's\ndocumented team workflow has developers commit to their repository — **unvalidated** on\n`kiota client generate` / `kiota plugin generate`. A repository (or pull request) containing a malicious\nper-client / per-plugin `outputPath` causes Kiota, when a developer or CI runs the documented regenerate\ncommand, to **(CWE-22) write the entire generated client to an arbitrary path outside the workspace** — the\n`outputPath` was not confined to the workspace root and absolute paths were accepted.\n\nConfirmed on Kiota **1.32.4** (`KIOTA_CONFIG_PREVIEW=true`, the self-contained `linux-x64` release binary).\n\n### Details\n\n```jsonc\n// .kiota/workspace.json (committed to the repo)\n\"clients\": { \"MyClient\": {\n   \"outputPath\": \"/abs/path/outside/repo/pwned_client\"   // -> generated client written here (CWE-22)\n}}\n```\n\nRunning `kiota client generate --client-name MyClient` in the repo writes `MyClient.cs`,\n`P/PRequestBuilder.cs`, … to the attacker-chosen `outputPath` (verified outside the working tree).\n\n#### Note on `descriptionLocation`\n\nThe per-consumer `descriptionLocation` is intentionally fetched at generation time — this is how Kiota knows\nwhere to pull an updated description from when refreshing a client, the same way any other value in a\ncommitted lock/config file is honored. It is **not** treated as a vulnerability and is unchanged; only\n`outputPath` is now confined.\n\n### Impact\n\nA malicious or compromised repository — or a malicious PR that edits `.kiota/workspace.json` — leads to\narbitrary file write on the developer's or CI host's filesystem (overwrite source/build files, drop files in\nauto-loaded locations) whenever a teammate clones/pulls and runs the documented `kiota client generate` /\n`kiota plugin generate` to refresh the client. CWE-22.\n\nThis is a different trust boundary from the OpenAPI-description-based findings: the malicious input is the\nKiota **config**, not the spec.\n\n### Patches\n\nFixed in **1.29.1 and 1.32.5** (https://github.com/microsoft/kiota/pull/7885). On loading a workspace configuration,\neach client/plugin `outputPath` is validated to be a relative subdirectory of the workspace: null/empty,\nrooted paths (POSIX `/`, UNC `\\\\` / `//`, Windows drive `X:\\`), and any `..` traversal segment are rejected,\nand the resolved full path must stay under the workspace root. Generation aborts with an error if any\nconsumer's `outputPath` escapes the workspace.\n\n### Remediation\n\nUpgrade to Kiota **1.29.1, 1.32.5** or later. Review any committed workspace configs for `outputPath` values that\npoint outside the workspace.","published":"2026-07-16T14:42:02.337Z","modified":"2026-10-07T07:05:28.664141470Z","cvss":null,"epss":{"score":0.01374,"percentile":0.70469,"asOf":"2026-09-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota","fixedVersion":"1.32.5"},{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota.Builder","fixedVersion":"1.32.5"},{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota","fixedVersion":"1.29.1"},{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota.Builder","fixedVersion":"1.29.1"}],"fix":{"url":"https://github.com/microsoft/kiota/commit/4049327872db7846ace35c9003774d3e3878e4e9","label":"microsoft/kiota@4049327"},"references":[{"type":"WEB","url":"https://github.com/microsoft/kiota/releases/tag/v1.32.5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59863.json"},{"type":"ADVISORY","url":"https://github.com/microsoft/kiota/security/advisories/GHSA-4rj6-vrwv-wr8m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59863"},{"type":"FIX","url":"https://github.com/microsoft/kiota/commit/4049327872db7846ace35c9003774d3e3878e4e9"},{"type":"FIX","url":"https://github.com/microsoft/kiota/pull/7885"},{"type":"PACKAGE","url":"https://github.com/microsoft/kiota"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-07T07:05:28.664141470Z"}}