Code Injection in Microsoft.OpenAPI.Kiota (CVE-2026-59862)
Summary
Code injection in Microsoft.OpenAPI.Kiota (CVE-2026-59862). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 1.29.1 or later.
Original description
The description as published by the source.
Code Generation Literal Injection in Kiota Python Generator Leads to Arbitrary Code Execution at Import Time.
The Kiota Python code generator is vulnerable to a code generation literal injection issue when processing malicious or untrusted OpenAPI specifications. Specifically, attacker-controlled enum value descriptions from x-ms-enum.values[].description can flow into generated Python files without newline sanitization, allowing injected content to escape a comment context and execute at module scope when the generated module is imported.
This issue requires user interaction in the form of generating a client from a malicious specification and importing the generated code, which is a common development and CI workflow.
Impact
A malicious OpenAPI specification can cause arbitrary Python code to be emitted into generated model files. The payload executes when the affected module is imported.
Potential impact includes
Credential theft from developer or CI environments
Exfiltration of environment variables and secrets
Source code disclosure
Persistence via regenerated backdoored client output
Who is impacted
Developers generating Python SDKs from external or untrusted OpenAPI specs
Teams with CI/CD automation that regenerates clients from remote specification URLs
Any environment importing generated Python modules before manual review
Vulnerability details
Two gaps combine to enable exploitation:
Enum description cleanup gap
In KiotaBuilder.SetEnumOptions, enum…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-59862 has been found in Microsoft.OpenAPI.Kiota.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Microsoft.OpenAPI.Kiota to 1.29.1 or later.
If unsure, ask your IT team or search "Microsoft.OpenAPI.Kiota CVE-2026-59862" on the vendor's site.
CVE-2026-59862 (Microsoft.OpenAPI.Kiota) — CWE-94 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.29.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Arbitrary code execution (CWE-94) exists in Microsoft.OpenAPI.Kiota.
Check the vendor advisory for the affected versions of Microsoft.OpenAPI.Kiota.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 1.29.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Microsoft.OpenAPI.Kiota' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'Microsoft.OpenAPI.Kiota' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Microsoft.OpenAPI.Kiotaを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Microsoft.OpenAPI.Kiota to 1.29.1ステージング環境で 1.29.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com