Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.32.5, Kiota emitted x-ms-kiota-info clientClassName and clientNamespaceName values without identifier or path sanitization as both generated client class or namespace names and generated output path components when kiota generate ran without -c/--class-name, allowing an attacker-controlled or compromised OpenAPI description to write generated source outside the -o output directory and inject arbitrary text into generated class or namespace declarations. This issue is fixed in version 1.32.5 by GenerationConfiguration.SanitizeClientClassName and SanitizeClientNamespaceName.
CVE-2026-59866
CRITICALPre-NVD 9.39.3
EchelonGraph scoreLOW confidence
This critical-severity CVE scores 9.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: secondary
9.3
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: —CVSS: 9.3Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 9.3
- EG Score
- 9.3(low)
- EPSS
- —
- KEV
- Not listed
Published
July 16, 2026
Last Modified
July 17, 2026
Advisory Details (4)
Auto-updated Jul 16, 2026Patch available. Sources: github_release, github, github_commit, github_pr.
github Patch Available
Arbitrary file write + code-injection via x-ms-kiota-info clientClassName and clientNamespaceName (Microsoft Kiota) · Advisory · microsoft/kiota · GitHub
https://github.com/microsoft/kiota/security/advisories/GHSA-4vv7-jj25-4gh6github_release Patch Available
v1.32.5
Patch available: microsoft/kiota v1.32.5
https://github.com/microsoft/kiota/releases/tag/v1.32.5github_pr
fix: sanitizes the client class and namespace names to avoid code injection
Fix merged in microsoft/kiota PR #7884 on 2026-07-01 — awaiting tagged release
https://github.com/microsoft/kiota/pull/7884github_commit
commit dc812dbbf88e (microsoft/kiota)
Fix landed in microsoft/kiota commit dc812dbbf88e — awaiting tagged release
https://github.com/microsoft/kiota/commit/dc812dbbf88ef7edf53a890d36b2f9d1460e947dWeakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 6× in last 7d / 6× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-17 05:57 UTCEG score recompute
- 2026-07-17 02:18 UTCEG score recompute
- 2026-07-16 22:40 UTCEG score recompute
- 2026-07-16 19:02 UTCEG score recompute
- 2026-07-16 15:24 UTCEG score recompute
- 2026-07-16 15:23 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-22 · CWE-94
Frequently asked(4)
What is CVE-2026-59866?
CVE-2026-59866 is a critical vulnerability published on July 16, 2026. Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.32.5, Kiota emitted x-ms-kiota-info clientClassName and clientNamespaceName values without identifier or path sanitization as both generated client class or namespace names and generated output path components when kiota generate ran…
When was CVE-2026-59866 disclosed?
CVE-2026-59866 was first published in the National Vulnerability Database on July 16, 2026, with the most recent update on July 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-59866?
CVE-2026-59866 has a CVSS v3 base score of 9.3 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-59866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59866, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-59866
Is Your Infrastructure Affected by CVE-2026-59866?
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