CVE-2026-59864: Microsoft Kiota: Path/URL injection into generated Copilot plugin manifest via x-ai-* extensions

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 1.3%, percentile 71: FIRST’s model estimates a 1.3% chance of exploitation activity in the next 30 days, higher than 71% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes Microsoft.OpenApi.Kiota (NuGet) >= 1.30.0, < 1.32.5, fixed in 1.32.5; Microsoft.OpenApi.Kiota.Builder (NuGet) >= 1.30.0, < 1.32.5, fixed in 1.32.5; Microsoft.OpenApi.Kiota (NuGet) < 1.29.1, fixed in 1.29.1; Microsoft.OpenApi.Kiota.Builder (NuGet) < 1.29.1, fixed in 1.29.1. Check your lockfile, including transitive dependencies.

What it is

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.32.5, kiota plugin add and kiota plugin generate (with -t APIPlugin) emitted attacker-controlled statictemplate.file values from x-ai-adaptive-card and x-ai-capabilities into generated Microsoft 365 Copilot and Teams plugin manifests without path validation, allowing ../, absolute, rooted, UNC, Windows drive, or URI paths in responsesemantics.statictemplate.file to cause path traversal or out-of-package file inclusion when the generated plugin was deployed. This issue is fixed in version 1.29.1 and 1.32.5.

From the GitHub advisory

Summary

kiota plugin add / kiota plugin generate (with -t APIPlugin) emits an attacker-controlled statictemplate.file path from the AI-plugin extensions (x-ai-adaptive-card, x-ai-capabilities) verbatim, with no path validation, into the generated Microsoft 365 Copilot / Teams plugin manifest ( -apiplugin.json). An attacker-controlled or compromised OpenAPI description can therefore embed a ../ / absolute path into the manifest's responsesemantics.statictemplate.file, yielding a path traversal (CWE-22) / out-of-package file inclusion (CWE-829) that is resolved by the AI host when the generated plugin is deployed.

Confirmed on Kiota 1.32.4 (KIOTACONFIGPREVIEW=true, the self-contained linux-x64 release binary).

Details

Both extension paths write the statictemplate.file reference straight into the manifest without sanitization — PluginsGenerationService.GetResponseSemanticsFromAdaptiveCardExtension mints statictemplate = {"file": }, and the x-ai-capabilities path copies the statictemplate object through:

Weakness type: CWE-22, CWE-829.

Product: Microsoft.OpenApi.Kiota (NuGet) · Assigned by: GitHub_M · Published: 2026-07-16

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.33% probability of exploitation activity in the next 30 days; percentile 71.

Timeline

• 2026-07-16 — CVE record published by GitHub_M
• 2026-07-24 — GitHub-reviewed advisory GHSA-4jwf-m4wg-8p66 published (critical)
• 2026-08-17 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-4jwf-m4wg-8p66 github.com
2. CVE.org record CVE-2026-59864 cve.org
3. NVD entry CVE-2026-59864 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

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