Skip to content

Microsoft Kiota: Path traversal in generated plugin manifest static_template.file reference (percent-encoding bypass)

Moderate severity GitHub Reviewed Published Jul 8, 2026 in microsoft/kiota • Updated Jul 24, 2026

Package

nuget Microsoft.OpenApi.Kiota (NuGet)

Affected versions

<= 1.33.0

Patched versions

1.34.0

Description

Impact

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 → ．．).

Patches

  • The percent-encoding bypass is fixed by decoding the reference (bounded multi-pass) before validation: microsoft/kiota#7910
  • Residual bypasses (NUL / control characters, decode-budget fail-open, Unicode homoglyphs) are fixed by failing closed on residual encoding, rejecting control characters, and NFKC-folding before validation: microsoft/kiota#7913 (tracking issue microsoft/kiota#7912)

Users should upgrade to the first released Microsoft.OpenApi.Kiota version that includes these fixes (the release following 1.33.0).

Workarounds

  • Only generate clients/plugins from trusted OpenAPI descriptions.
  • Review generated plugin manifests before deployment and reject any 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).

References

  • CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
  • CWE-829: Inclusion of Functionality from an Untrusted Control Sphere
  • Affected code: src/Kiota.Builder/OpenApiExtensions/OpenApiAiCapabilitiesExtension.cs (IsSafeFileReference) and enforcement in src/Kiota.Builder/Plugins/PluginsGenerationService.cs.

References

@gavinbarron gavinbarron published to microsoft/kiota Jul 8, 2026
Published to the GitHub Advisory Database Jul 24, 2026
Reviewed Jul 24, 2026
Last updated Jul 24, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction Active
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality High
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N

EPSS score

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

Inclusion of Functionality from Untrusted Control Sphere

The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-p5rm-jg5c-8c77

Source code

Credits

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.