CVE-2026-105796: Microsoft Kiota documentation-comment injection in Java and PHP

CVE-2026-105796 · Severity: high · CVSS 8.8 · Published 2026-10-06

Kiota is a code generator that creates HTTP clients from API specifications. Versions 0.5.0 through 1.34.x contain a flaw where malicious API descriptions can inject executable code into generated Java and PHP source files. An attacker can craft a malicious OpenAPI schema that, when processed by Kiota, produces code with injected commands that execute during compilation or runtime in the developer's or build pipeline's environment.

Technologies: Microsoft Kiota, Microsoft.OpenApi.Kiota (NuGet), Microsoft.OpenApi.Kiota.Builder (NuGet). Vendors: Microsoft, NuGet.

Quick answers

Is CVE-2026-105796 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-105796 being exploited in the wild.
How severe is CVE-2026-105796?
High severity, with a CVSS score of 8.8, published 6 October 2026.
Which products and versions are affected?
Microsoft Kiota 0.5.0 to 1.34.x; Microsoft.OpenApi.Kiota (NuGet) >= 0.5.0, < 1.35.0, ECOSYSTEM:introduced=0.5.0,fixed=1.35.0; Microsoft.OpenApi.Kiota.Builder (NuGet) >= 0.5.0, < 1.35.0, ECOSYSTEM:introduced=0.5.0,fixed=1.35.0.
Is there a fix for CVE-2026-105796?
Yes. Microsoft.OpenApi.Kiota (NuGet): upgrade to 1.35.0 or later; Microsoft.OpenApi.Kiota.Builder (NuGet): upgrade to 1.35.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-105796 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-105796?
Check whether you run Microsoft Kiota, Microsoft.OpenApi.Kiota (NuGet) or Microsoft.OpenApi.Kiota.Builder (NuGet) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Microsoft.OpenApi.Kiota (NuGet): upgrade to 1.35.0 or later
    dotnet add package Microsoft.OpenApi.Kiota --version 1.35.0
  • Microsoft.OpenApi.Kiota.Builder (NuGet): upgrade to 1.35.0 or later
    dotnet add package Microsoft.OpenApi.Kiota.Builder --version 1.35.0

Technical details

The Java and PHP documentation-comment sanitizers deleted block-comment terminators (/* and */) rather than neutralizing them, allowing attacker-controlled text in OpenAPI descriptions to escape documentation comments and inject arbitrary code. The Java sanitizer also removed non-ASCII characters after terminator deletion, which could recreate a terminator during normalization. Exploitation requires a developer or build pipeline to generate and compile/load code from a malicious OpenAPI schema.

Affected products

  • Microsoft Kiota 0.5.0 to 1.34.x

Identifiers

  • CVE-2026-105796
  • GHSA-rm89-rhwj-9j92

Timeline

  • 2026-08-10: patched: Fix merged replacing delimiters instead of deleting them
  • 2026-10-06: disclosed

References

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