CVE-2026-59861Network attack vector

Arbitrary code execution via Ruby interpolation

Published Jul 16, 2026 · Updated Jul 16, 2026

Code injection in Microsoft Kiota before 1.29.1 and 1.30.0 through 1.31.1 allows remote attackers to execute code via crafted OpenAPI. CodeMethodWriter.cs emits schema defaults, wire names, mappings, and indexer keys into double-quoted Ruby literals without escaping # interpolation markers. Exploitation requires an untrusted specification to be processed for Ruby output and the generated model code to be loaded by a developer, pipeline, or application.

CVSS severity7.5
High
EPSS probability2.05%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in Microsoft Kiota before 1.29.1 and 1.30.0 through 1.31.1 allows remote attackers to execute code via crafted OpenAPI. CodeMethodWriter.cs emits schema defaults, wire names, mappings, and indexer keys into double-quoted Ruby literals without escaping # interpolation markers. Exploitation requires an untrusted specification to be processed for Ruby output and the generated model code to be loaded by a developer, pipeline, or application.

The record

CVE
CVE-2026-59861
Published
Jul 16, 2026
Updated
Jul 16, 2026
Vendor
Microsoft
Product
Kiota
Classifications
CWE-94, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.32.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Kiotaversion=< 1.32.0

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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