{"id":"GHSA-rg4h-fpcp-2qm8","summary":"Microsoft Kiota: Generation-time SSRF + remote/local file inclusion via unrestricted $ref","details":"## Summary\n\nMicrosoft Kiota resolved OpenAPI `$ref`s by fetching remote `http(s)` URLs and reading local files\n(including absolute / out-of-tree paths), inlining the referenced schema into the generated client.\nRunning `kiota generate` on a spec whose `$ref` pointed at an attacker/internal URL or an arbitrary\nlocal file yielded SSRF, remote file inclusion, and local file inclusion. Verified on **1.32.3 / 1.32.4**.\n\n### Details\n\n- `$ref: http://attacker/internal-evil.json#/...` → build host fetches the URL (SSRF) and inlines the\n  remote schema (RFI); confirmed property `REMOTE_KIOTA_PROP` in the generated client.\n- `$ref: /abs/path.json#/...` or `../../secret.json#/...` → Kiota reads the out-of-tree local file and\n  inlines its schema (LFI); confirmed `Leaked` schema in the generated client. Resolution is transitive\n  across nesting levels.\n\nKiota **escapes** its output sinks (comments/strings/identifiers), so attacker-controlled remote/local\ncontent cannot break out into code — no RCE. The chain stops at SSRF + RFI + LFI.\n\n### Impact\n\nBuild-time SSRF (CWE-918) from the developer or CI host, disclosure of arbitrary local files (CWE-22), and\ninclusion of untrusted remote content (CWE-829), from running the generator on an attacker-controlled or\nattacker-influenced OpenAPI description. No code execution. Notable because Kiota is otherwise the hardened\ngenerator (it resists the code-injection class).\n\nThe relevant threat is not \"change the generated output\" (an attacker who fully controls the description can\nalready do that) but the **side effects on the build host**: outbound requests from inside the CI network\n(cloud metadata, internal-only services) and reads of local files the attacker never possessed, whose contents\nare then inlined into the generated — and typically committed/published — client. It also bypasses controls\nthat review the description document but not externally-referenced content.\n\n### Patches\n\nFixed in **1.29.1 and 1.32.5** (https://github.com/microsoft/kiota/pull/7888). External reference resolution is now\n**default-deny**: a new `AllowedExternalOriginsStreamLoader` refuses to load any external `$ref` — remote\n`http(s)` URLs and local file paths alike — unless its origin/path is explicitly allow-listed. A new\n`--allowed-external-origins` parameter (added to the commands that load OpenAPI descriptions) opts specific\norigins back in, accepting `*`, full URIs, URI patterns, full paths, relative paths, or path patterns\n(wildcards supported). With no allow-list entries, external references are not loaded at all.\n\n### Remediation\n\nUpgrade to Kiota **1.29.1, 1.32.5,** or later. External references now require explicit opt-in via\n`--allowed-external-origins`; add only trusted origins/paths.","aliases":["CVE-2026-59867"],"modified":"2026-08-17T15:00:08.066449664Z","published":"2026-07-24T16:10:17Z","database_specific":{"github_reviewed_at":"2026-07-24T16:10:17Z","nvd_published_at":"2026-07-16T16:19:15Z","cwe_ids":["CWE-22","CWE-829","CWE-918"],"severity":"HIGH","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/microsoft/kiota/security/advisories/GHSA-rg4h-fpcp-2qm8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59867"},{"type":"WEB","url":"https://github.com/microsoft/kiota/pull/7888"},{"type":"WEB","url":"https://github.com/microsoft/kiota/commit/cccd798027f0a20db796b3df6c64f9897a39d7b1"},{"type":"PACKAGE","url":"https://github.com/microsoft/kiota"},{"type":"WEB","url":"https://github.com/microsoft/kiota/releases/tag/v1.32.5"}],"affected":[{"package":{"name":"Microsoft.OpenApi.Kiota","ecosystem":"NuGet","purl":"pkg:nuget/Microsoft.OpenApi.Kiota"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.30.0"},{"fixed":"1.32.5"}]}],"versions":["1.30.0","1.31.0","1.31.1","1.32.0","1.32.1","1.32.2","1.32.3","1.32.4"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-rg4h-fpcp-2qm8/GHSA-rg4h-fpcp-2qm8.json"}},{"package":{"name":"Microsoft.OpenApi.Kiota.Builder","ecosystem":"NuGet","purl":"pkg:nuget/Microsoft.OpenApi.Kiota.Builder"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.30.0"},{"fixed":"1.32.5"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-rg4h-fpcp-2qm8/GHSA-rg4h-fpcp-2qm8.json"}},{"package":{"name":"Microsoft.OpenApi.Kiota","ecosystem":"NuGet","purl":"pkg:nuget/Microsoft.OpenApi.Kiota"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.29.1"}]}],"versions":["0.1.0-preview","0.1.1-preview","0.1.2-preview","0.1.3-preview","0.10.0-preview","0.11.0-preview","0.11.1-preview","0.2.0-preview","0.2.1-preview","0.3.0-preview","0.4.0-preview","0.5.0-preview","0.5.1-preview","0.6.0-preview","0.7.1-preview","0.8.3-preview","0.9.0-preview","1.0.0","1.0.1","1.1.0","1.1.1","1.1.2","1.1.3","1.10.0","1.10.1","1.11.0","1.11.1","1.12.0","1.13.0","1.14.0","1.15.0","1.16.0","1.17.0","1.18.0","1.19.0","1.19.1","1.2.0","1.2.1","1.20.0","1.21.0","1.22.0","1.22.1","1.22.2","1.22.3","1.23.0","1.24.0","1.24.1","1.24.2","1.24.3","1.25.1","1.26.0","1.26.1","1.27.0","1.28.0","1.29.0","1.3.0","1.4.0","1.5.0","1.5.1","1.6.1","1.7.0","1.8.0","1.8.1","1.8.2","1.9.0","1.9.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-rg4h-fpcp-2qm8/GHSA-rg4h-fpcp-2qm8.json"}},{"package":{"name":"Microsoft.OpenApi.Kiota.Builder","ecosystem":"NuGet","purl":"pkg:nuget/Microsoft.OpenApi.Kiota.Builder"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.29.1"}]}],"versions":["0.2.0-preview","0.3.0-preview","0.4.0-preview","0.5.0-preview","0.5.1-preview","0.6.0-preview","0.7.1-preview","1.0.0","1.0.1","1.1.0","1.1.1","1.1.2","1.1.3","1.10.0","1.10.1","1.11.0","1.11.1","1.12.0","1.13.0","1.14.0","1.15.0","1.16.0","1.17.0","1.18.0","1.19.0","1.19.1","1.2.0","1.2.1","1.20.0","1.21.0","1.22.0","1.22.1","1.22.2","1.22.3","1.23.0","1.3.0","1.4.0","1.5.0","1.5.1","1.6.1","1.7.0","1.8.0","1.8.1","1.8.2","1.9.0","1.9.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-rg4h-fpcp-2qm8/GHSA-rg4h-fpcp-2qm8.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N"}]}