[GHSA-rg4h-fpcp-2qm8] Microsoft Kiota: Generation-time SSRF + remote/local file inclusion via unrestricted $ref

advisories/github-reviewed/2026/07/GHSA-rg4h-fpcp-2qm8/GHSA-rg4h-fpcp-2qm8.json

@@ -1,13 +1,13 @@
 {
   "schema_version": "1.4.0",
   "id": "GHSA-rg4h-fpcp-2qm8",
-  "modified": "2026-08-17T14:56:30Z",
+  "modified": "2026-08-17T14:56:31Z",
   "published": "2026-07-24T16:10:17Z",
   "aliases": [
     "CVE-2026-59867"
   ],
   "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.",
+  "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 **1.32.5** (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 **1.32.5** or later. External references now require explicit opt-in via\n`--allowed-external-origins`; add only trusted origins/paths.",
   "severity": [
     {
       "type": "CVSS_V3",
@@ -56,7 +56,7 @@
     {
       "package": {
         "ecosystem": "NuGet",
-        "name": "Microsoft.OpenApi.Kiota"
+        "name": "Microsoft.OpenApi.Kiota.Builder"
       },
       "ranges": [
         {
@@ -75,7 +75,7 @@
     {
       "package": {
         "ecosystem": "NuGet",
-        "name": "Microsoft.OpenApi.Kiota.Builder"
+        "name": "Microsoft.OpenApi.Kiota"
       },
       "ranges": [
         {