# CVE-2026-41134: Microsoft.OpenApi.Kiota — Fixed in 1.31.1 .NET NuGet Not in CISA KEV # CVE-2026-41134 — Microsoft.OpenApi.Kiota CVE-2026-41134 is a Code Injection vulnerability in Microsoft.OpenApi.Kiota. A fix is available for Microsoft.OpenApi.Kiota — see the affected versions and patch details below. Kiota: Code Generation Literal Injection Also known as[GHSA-2hx3-vp6r-mg3f](/vulnerability/GHSA-2hx3-vp6r-mg3f) Published Apr 22, 2026 Updated Nov 7, 2026 Affected 4 pkgs Patched 4 / 4 Exploits None indexed Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS) ## Exploitation Status ### No confirmed exploitation observed yet - A successful exploit gives an attacker total control of the affected component, not partial access. - CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment. Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41134. ## EPSS Exploitation Probability [via FIRST.org ↗](https://www.first.org/epss/) 0.4%probability of exploitation in next 30 days Lower Risk0.00% Lower risk than most CVEs37th percentile — riskier than 37% of all scored CVEsHighest risk 0.00%0.31%0.61%0.92%0.1%0.4%May 26Sep 26Nov 26 Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/). ## Real-World Exposure 4 pkgs affected .NET`Microsoft.OpenApi.Kiota`.NET`Microsoft.OpenApi.Kiota.Builder`.NET`Microsoft.OpenApi.Kiota`.NET`Microsoft.OpenApi.Kiota.Builder` Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems. ## Description ## CVE Advisory (CVE-2026-41134): Code Generation Literal Injection in Kiota ### Summary Kiota versions **prior to 1.29.1 and 1.31.1** are affected by a code-generation literal injection vulnerability in multiple writer sinks (for example: serialization/deserialization keys, path/query parameter mappings, URL template metadata, enum/property metadata, and default value emission). When malicious values from an OpenAPI description are emitted into generated source without context-appropriate escaping, an attacker can break out of string literals and inject additional code into generated clients. ### Impact and Preconditions This issue is only practically exploitable when: 1. the OpenAPI description used for generation is from an **untrusted source**, or 2. a normally trusted OpenAPI description has been **compromised/tampered with**. If you only generate from trusted, integrity-protected API descriptions, risk is significantly reduced. ### Affected Versions - **Affected:** all versions **< 1.29.1** and **\>= 1.30.0, < 1.31.1** - **Fixed:** **1.29.1, 1.31.1,** and later ### Illustrative Exploit Example #### Example OpenAPI fragment (malicious default value) ``` openapi: 3.0.1 info: title: Exploit Demo version: 1.0.0 components: schemas: User: type: object properties: displayName: type: string default: "\"; throw new System.Exception(\"injected\"); //" ``` #### Example generated C# snippet before fix (illustrative) ``` public User() { DisplayName = ""; throw new System.Exception("injected"); //"; } ``` The injected payload escapes the intended string context and introduces attacker-controlled statements in generated code. > Note: this exploit is not limited to default values, but may also impact properties names (serialization), path or query parameters, enum representations and other locations. ### Remediation 1. Upgrade Kiota to **1.31.1 or later**. 2. Regenerate/refresh existing generated clients as a precaution: ``` kiota update ``` Refreshing generated clients ensures previously generated vulnerable code is replaced with hardened output. ### Acknowledgement We would like to thank the researcher Thanatos Tian（Polyu) for finding this issue and for his contribution to this open source project. ## Affected Packages 4 total 4 fixed Ecosystem Package Vulnerable range Fix .NETNuGet `Microsoft.OpenApi.Kiota` ≥ 1.30.0&&< 1.31.1 1.31.1`dotnet add package Microsoft.OpenApi.Kiota --version 1.31.1` .NETNuGet `Microsoft.OpenApi.Kiota.Builder` ≥ 1.30.0&&< 1.31.1 1.31.1`dotnet add package Microsoft.OpenApi.Kiota.Builder --version 1.31.1` .NETNuGet `Microsoft.OpenApi.Kiota` all versions 1.29.1`dotnet add package Microsoft.OpenApi.Kiota --version 1.29.1` .NETNuGet `Microsoft.OpenApi.Kiota.Builder` all versions 1.29.1`dotnet add package Microsoft.OpenApi.Kiota.Builder --version 1.29.1` ## Affected Products 1 product · 1 configurations Application `kiota`microsoft < 1.31.1 range ## Detection & mitigation playbook Open-source dependency 1. ### Detect Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.OpenApi.Kiota, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version. 2. ### Fix Update Microsoft.OpenApi.Kiota to 1.31.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41134 is resolved across your whole dependency graph. 3. ### Workarounds Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does. ## Frequently Asked Questions \# CVE Advisory (CVE-2026-41134): Code Generation Literal Injection in Kiota ## Summary Kiota versions \*\*prior to 1.29.1 and 1.31.1\*\* are affected by a code-generation literal injection vulnerability in multiple writer sinks (for example: serialization/deserialization keys, path/query parameter mappings, URL template metadata, enum/property metadata, and default value emission). When malicious values from an OpenAPI description are emitted into generated source without context-appropriate escaping, an attacker can break out of string literals and inject additional code into generated clients O3 Security · Impact-Aware SCA ### Is CVE-2026-41134 in your dependencies? Find it across NuGet, including transitive dependencies. [Scan my dependencies](/book-demo) [How O3 SCA works](/impact-aware-sca)