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PatchSiren cyber security CVE debrief

CVE-2026-59859 microsoft CVE debrief

CVE-2026-59859 is a vulnerability in Kiota, an OpenAPI based HTTP Client code generator. Prior to version 1.32.4, Kiota's PHP generator embedded OpenAPI description, default fields, property names, and other schema-derived strings into PHP double-quoted literals without proper escaping, allowing for code injection. This issue allows attackers to inject arbitrary PHP code into generated model and request-builder classes. The vulnerability exists due to insufficient sanitization of user-controlled input in the PHP generator. Developers and administrators using Kiota's PHP generator should be aware of this vulnerability and take steps to mitigate it by updating to version 1.32.4 or later.

Vendor
microsoft
Product
kiota
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-16
Original CVE updated
2026-08-17
Advisory published
2026-07-16
Advisory updated
2026-08-17

Who should care

Developers and administrators using Kiota's PHP generator should be aware of this vulnerability and take steps to mitigate it by updating to version 1.32.4 or later. This includes reviewing generated PHP code for potential code injection vulnerabilities and implementing additional security measures to prevent code injection attacks. Affected operators and platforms should prioritize updates and vulnerability management.

Technical summary

The vulnerability exists in Kiota's PHP generator, where OpenAPI description, default fields, property names, and other schema-derived strings are embedded into PHP double-quoted literals through SanitizeDoubleQuote() in Writers/StringExtensions.cs without escaping $, allowing attacker-controlled ${...}, $var, or {$obj->prop} interpolation constructs to inject arbitrary PHP code into generated model and request-builder classes. This issue is fixed in version 1.32.4. Affected product context requires defensive impact assessment and source-grounded technical framing.

Defensive priority

High

Recommended defensive actions

  • Update Kiota to version 1.32.4 or later
  • Review generated PHP code for potential code injection vulnerabilities
  • Implement additional security measures to prevent code injection attacks
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record was published on 2026-07-16T15:16:35.167Z and has not been modified since then. The NVD entry is currently Deferred. Evidence is limited to CVE and NVD information. Defenders should verify affected Kiota deployments and review generated PHP code.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-59859 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-59859

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-59859 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-59859

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.