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High, CVSS 7.0

Microsoft Kiota Workspace-config poisoning: out-of-repo file write + generation-time SSRF

CVE-2026-59863GHSA-4rj6-vrwv-wr8m

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (microsoft.openapi.kiota 1.32.5, 1.29.1; microsoft.openapi.kiota.builder 1.32.5, 1.29.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
7.0 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-59863: 1.37% estimated exploitation activity in the next 30 days; percentile 72.05 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Microsoft Kiota honors a poisoned .kiota/workspace.json — the workspace configuration that Kiota's documented team workflow has developers commit to their repository — unvalidated on kiota client generate / kiota plugin generate. A repository (or pull request) containing a malicious per-client / per-plugin outputPath causes Kiota, when a developer or CI runs the documented regenerate command, to (CWE-22) write the entire generated client to an arbitrary path outside the workspace — the outputPath was not confined to the workspace root and absolute paths were accepted. Confirmed on Kiota 1.32.4 (KIOTACONFIGPREVIEW=true, the self-contained linux-x64 release binary). Details Running kiota client generate --client-name MyClient in the repo writes MyClient.cs, P/PRequestBuilder.cs, … to the attacker-chosen outputPath (verified outside the working tree). Note on descriptionLocation The per-consumer descriptionLocation is intentionally fetched at generation time — this is how Kiota…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-4rj6-vrwv-wr8m

Agent brief

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# Patch Next advisory brief: CVE-2026-59863

Advisory: Microsoft Kiota Workspace-config poisoning: out-of-repo file write + generation-time SSRF
IDs: CVE-2026-59863, GHSA-4rj6-vrwv-wr8m
Record: https://patchnext.com/advisories/cve-2026-59863 (revision 1, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: microsoft.openapi.kiota 1.32.5, 1.29.1; microsoft.openapi.kiota.builder 1.32.5, 1.29.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet microsoft.openapi.kiota: affected >= 1.30.0, < 1.32.5; < 1.29.1; fixed in 1.29.1, 1.32.5
- NuGet microsoft.openapi.kiota.builder: affected >= 1.30.0, < 1.32.5; < 1.29.1; fixed in 1.29.1, 1.32.5

## Suggested inspection (read-only)
- NuGet microsoft.openapi.kiota: check the installed version with your package manager.
- NuGet microsoft.openapi.kiota.builder: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on microsoft.openapi.kiota, microsoft.openapi.kiota.builder.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4rj6-vrwv-wr8m (GitHub-reviewed advisory GHSA-4rj6-vrwv-wr8m lists affected ranges: NuGet microsoft.openapi.kiota >=1.30.0 =0 =1.30.0 =0 <1.29.1)

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