RCE in Microsoft Kiota

CVE-2026-59861

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.32.0, Kiota's Ruby generator embedded OpenAPI default fields, property names, and other schema-derived strings through CodeMethodWriter.cs and SanitizeForQuotedLiteral() in Writers/StringExtensions.cs into Ruby double-quoted literals without escaping #, allowing attacker-controlled #{expr}, #$var, or #@var interpolation markers to inject arbitrary Ruby code into generated model classes. This issue is fixed in version 1.29.1 and 1.32.0.

Vulnerability class: RCE (Remote Code Execution)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.020 (81.1th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 81st percentile — 81.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-59861: held from 0.020 to 0.020.

EPSS over last 30 days · oldest: 0.020 · newest: 0.020 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-59861?
CVE-2026-59861 is a high-severity vulnerability in Microsoft Kiota, classified under Code Injection. CVSS score: 7.5/10. Published 2026-07-16.
How severe is CVE-2026-59861?
High severity. CVSS v3 base score is 7.5 out of 10.