Vulnerability-Lookup

CVE-2026-59860 (GCVE-0-2026-59860)

Vulnerability from cvelistv5 – Published: 2026-07-16 14:34 – Updated: 2026-08-17 15:01

Title

Kiota: XML Doc-Comment Newline Breakout Code Injection

Summary

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.32.3, Kiota is affected by a code-generation injection vulnerability in the C# XML documentation-comment sink (the description, externalDocs label, and externalDocs link fields emitted as /// … comments). When text from an OpenAPI description is written into single-line XML doc comments without stripping newline and Unicode line-terminator characters, an attacker can break out of the /// comment line and inject additional code into generated C# clients. This issue is fixed in version 1.29.1 and 1.32.3.

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-17 03:56 UTC

CWE

CWE-94 - Improper Control of Generation of Code ('Code Injection')

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/microsoft/kiota/security/advis…	x_refsource_CONFIRM
https://github.com/microsoft/kiota/pull/7831	x_refsource_MISC
https://github.com/microsoft/kiota/commit/ebb632d…	x_refsource_MISC
https://github.com/microsoft/kiota/releases/tag/v1.32.3	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
microsoft	kiota	Affected: >= 1.30.0, < 1.31.1 Affected: < 1.29.1	guessed

Show details on NVD website

JSON

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FKIE_CVE-2026-59860

Vulnerability from fkie_nvd - Published: 2026-07-16 15:16 - Updated: 2026-08-17 15:16

Severity

8.7 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/microsoft/kiota/commit/ebb632db90aa8e3c20949337d9faa2720d64ca44
	security-advisories@github.com	https://github.com/microsoft/kiota/pull/7831
	security-advisories@github.com	https://github.com/microsoft/kiota/releases/tag/v1.32.3
	security-advisories@github.com	https://github.com/microsoft/kiota/security/advisories/GHSA-3hrf-2gc2-mx32
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/microsoft/kiota/security/advisories/GHSA-3hrf-2gc2-mx32

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          "product": "kiota",
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GHSA-3HRF-2GC2-MX32

Vulnerability from github – Published: 2026-07-24 15:30 – Updated: 2026-08-17 14:52

Summary

Microsoft Kiota: XML Doc-Comment Newline Breakout Code Injection

Details

Summary

Kiota versions prior to 1.32.3 and 1.29.1 are affected by a code-generation injection vulnerability in the C# XML documentation-comment sink (the description, externalDocs label, and externalDocs link fields emitted as /// … comments).

When text from an OpenAPI description is written into single-line XML doc comments without stripping newline and Unicode line-terminator characters, an attacker can break out of the /// comment line and inject additional code into generated C# clients.

Impact and Preconditions

This issue is only practically exploitable when:

the OpenAPI description used for generation is from an untrusted source, or
a normally trusted OpenAPI description has been compromised/tampered with.

The injected code is compiled (and may execute) when the developer or CI builds the generated client. If you only generate from trusted, integrity-protected API descriptions, risk is significantly reduced.

Affected Versions

Affected: all versions < 1.29.1, >= 1.30.0, < 1.32.3
Fixed: 1.29.1, 1.32.3, and later

Illustrative Exploit Example

Example OpenAPI fragment (malicious description)

openapi: 3.0.1
info:
  title: Exploit Demo
  version: 1.0.0
  description: |-
    Legitimate summary text
    public static class Pwned { static Pwned() { System.Diagnostics.Process.Start("calc.exe"); } }

The newline inside description (also exploitable via \r, U+0085, U+2028, U+2029) terminates the doc-comment line.

Example generated C# snippet before fix (illustrative)

/// Legitimate summary text
public static class Pwned { static Pwned() { System.Diagnostics.Process.Start("calc.exe"); } }

The injected payload escapes the intended /// comment context and introduces attacker-controlled statements in generated code.

Note: this exploit is not limited to the description field, but may also impact the externalDocs label and link text and other doc-comment-derived locations.

Remediation

Upgrade Kiota to 1.32.3 or later.
Regenerate/refresh existing generated clients as a precaution:

Refreshing generated clients ensures previously generated vulnerable code is replaced with hardened output. The fix (PR microsoft/kiota#7831) strips \r, \n, \u0085, \u2028, \u2029 (and normalizes tabs) from description, label, and link text before emitting doc comments.

Severity

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Microsoft.OpenApi.Kiota"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.30.0"
            },
            {
              "fixed": "1.32.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Microsoft.OpenApi.Kiota.Builder"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.30.0"
            },
            {
              "fixed": "1.32.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Microsoft.OpenApi.Kiota"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.29.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Microsoft.OpenApi.Kiota.Builder"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.29.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-59860"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-24T15:30:47Z",
    "nvd_published_at": "2026-07-16T15:16:35Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nKiota versions **prior to 1.32.3 and 1.29.1** are affected by a code-generation injection vulnerability in the C# XML documentation-comment sink (the `description`, `externalDocs` label, and `externalDocs` link fields emitted as `/// \u2026` comments).\n\nWhen text from an OpenAPI description is written into single-line XML doc comments without stripping newline and Unicode line-terminator characters, an attacker can break out of the `///` comment line and inject additional code into generated C# clients.\n\n## Impact and Preconditions\n\nThis issue is only practically exploitable when:\n\n1.  the OpenAPI description used for generation is from an **untrusted source**, or\n2.  a normally trusted OpenAPI description has been **compromised/tampered with**.\n\nThe injected code is compiled (and may execute) when the developer or CI **builds** the generated client. If you only generate from trusted, integrity-protected API descriptions, risk is significantly reduced.\n\n## Affected Versions\n\n- **Affected:** all versions **\u003c 1.29.1**, **\u003e= 1.30.0, \u003c 1.32.3**\n- **Fixed: 1.29.1, 1.32.3,** and later\n\n## Illustrative Exploit Example\n\n### Example OpenAPI fragment (malicious description)\n\n```yaml\nopenapi: 3.0.1\ninfo:\n  title: Exploit Demo\n  version: 1.0.0\n  description: |-\n    Legitimate summary text\n    public static class Pwned { static Pwned() { System.Diagnostics.Process.Start(\"calc.exe\"); } }\n```\n\nThe newline inside `description` (also exploitable via `\\r`, U+0085, U+2028, U+2029) terminates the doc-comment line.\n\n### Example generated C# snippet before fix (illustrative)\n\n```csharp\n/// Legitimate summary text\npublic static class Pwned { static Pwned() { System.Diagnostics.Process.Start(\"calc.exe\"); } }\n```\n\nThe injected payload escapes the intended `///` comment context and introduces attacker-controlled statements in generated code.\n\n\u003e Note: this exploit is not limited to the `description` field, but may also impact the `externalDocs` label and link text and other doc-comment-derived locations.\n\n## Remediation\n\n1.  Upgrade Kiota to **1.32.3 or later**.\n2.  Regenerate/refresh existing generated clients as a precaution:\n\nRefreshing generated clients ensures previously generated vulnerable code is replaced with hardened output. The fix (PR microsoft/kiota#7831) strips `\\r`, `\\n`, `\\u0085`, `\\u2028`, `\\u2029` (and normalizes tabs) from description, label, and link text before emitting doc comments.",
  "id": "GHSA-3hrf-2gc2-mx32",
  "modified": "2026-08-17T14:52:01Z",
  "published": "2026-07-24T15:30:47Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/kiota/security/advisories/GHSA-3hrf-2gc2-mx32"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59860"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/kiota/pull/7831"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/kiota/commit/ebb632db90aa8e3c20949337d9faa2720d64ca44"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/microsoft/kiota"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/kiota/releases/tag/v1.32.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Microsoft Kiota: XML Doc-Comment Newline Breakout Code Injection"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-59860 (GCVE-0-2026-59860)

FKIE_CVE-2026-59860

GHSA-3HRF-2GC2-MX32

Summary

Impact and Preconditions

Affected Versions

Illustrative Exploit Example

Example OpenAPI fragment (malicious description)

Example generated C# snippet before fix (illustrative)

Remediation

Tags

Sightings

Nomenclature

Related by attack behaviour