{"id":"CVE-2026-59863","aliases":["GHSA-4rj6-vrwv-wr8m"],"title":"Microsoft Kiota Workspace-config poisoning: out-of-repo file write + generation-time SSRF","summary":"Microsoft Kiota Workspace-config poisoning: out-of-repo file write + generation-time SSRF","severity":"high","cwe":["CWE-22","CWE-829","CWE-918"],"vendor":"Microsoft","product":"Microsoft.OpenApi.Kiota","ecosystem":"nuget","affected":["Microsoft.OpenApi.Kiota < 1.32.5","Microsoft.OpenApi.Kiota.Builder < 1.32.5"],"patched":["Microsoft.OpenApi.Kiota 1.32.5","Microsoft.OpenApi.Kiota.Builder 1.32.5"],"published":"2026-07-24","updated":"2026-07-24","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-4rj6-vrwv-wr8m","references":[{"url":"https://github.com/microsoft/kiota/security/advisories/GHSA-4rj6-vrwv-wr8m"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59863"},{"url":"https://github.com/microsoft/kiota/pull/7885"},{"url":"https://github.com/microsoft/kiota/commit/4049327872db7846ace35c9003774d3e3878e4e9"},{"url":"https://github.com/microsoft/kiota/releases/tag/v1.32.5"},{"url":"https://github.com/advisories/GHSA-4rj6-vrwv-wr8m"}],"tags":["ghsa","nuget"],"epss":0.01374,"epssPercentile":0.70805,"ingestedAt":"2026-07-24T16:33:09.683Z","slug":"CVE-2026-59863","body":"## Overview\n\n### 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 **1.32.5** (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 **1.32.5** or later. Review any committed workspace configs for `outputPath` values that\npoint outside the workspace.\n\n## Affected packages\n\n- `Microsoft.OpenApi.Kiota < 1.32.5`\n- `Microsoft.OpenApi.Kiota.Builder < 1.32.5`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `Microsoft.OpenApi.Kiota 1.32.5`\n- `Microsoft.OpenApi.Kiota.Builder 1.32.5`","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":41.3,"likelihood":0.3,"exploitation":0,"ransomware":0},"changes":[]}