NuGet · Microsoft.OpenApi.Kiota
Microsoft Kiota: Path traversal in generated plugin manifest static_template.file reference (percent-encoding bypass)
Kiota generates AI plugin manifests from an OpenAPI description. When the description contains an x-ai-capabilities response semantics static_template (or the adaptive-card extension x-ai-adaptive-card), the file reference is written into the generated manifest's response_semantics.static_template.file and is later resolved by the AI host relative to the plugin package.
An attacker who controls or tampers with the OpenAPI description consumed by Kiota can supply a file reference that resolves outside the manifest package (e.g. ../../../../etc/passwd, an absolute path, or a file:// / http(s):// URI). When the generated manifest is deployed and consumed by an AI host, this can lead to inclusion or disclosure of files outside the intended package boundary (CWE-22 Path Traversal, CWE-829 Inclusion of Functionality from an Untrusted Control Sphere).
A mitigation shipped in v1.32.5 (ExtensionResponseSemanticsStaticTemplate.IsSafeFileReference) rejected literal traversal, rooted paths, drive-qualified paths, and absolute URIs. However, that check inspected the raw reference string, so percent-encoded payloads bypassed every check and were still emitted verbatim. Examples that were incorrectly accepted as safe:
| Input | Decodes to |
|---|---|
%2e%2e/card.json |
../card.json |
..%2f..%2f..%2f..%2f..%2f..%2fetc%2fpasswd |
../../../../../../etc/passwd |
file%3A%2F%2F%2Fetc%2Fpasswd |
file:///etc/passwd |
%2e%2e%2f%2e%2e%2f%2e%2e%2fetc%2fpasswd |
../../../etc/passwd |
Multi-level (double) encoding such as %252e%252e%252fcard.json was also affected. A follow-up review found additional residual bypasses of the same validator: an embedded NUL byte (%00) that truncated the path and defeated the parent-directory segment check, encoding nested deeper than the decode budget (which failed open), and Unicode full-width homoglyphs (e.g. %EF%BC%8E%EF%BC%8E → ．．).
Users should upgrade to the first released Microsoft.OpenApi.Kiota version that includes these fixes (the release following 1.33.0).
response_semantics.static_template.file value that is not a simple relative path within the adaptiveCards/ package folder (no .., no rooted/absolute paths, no URIs, no percent-encoded separators).src/Kiota.Builder/OpenApiExtensions/OpenApiAiCapabilitiesExtension.cs (IsSafeFileReference) and enforcement in src/Kiota.Builder/Plugins/PluginsGenerationService.cs.Is your project exposed to this? Stateward checks every dependency on every pull request and flags it only if your code actually reaches it.
Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.