# CVE-2026-29791: agentgateway — Fixed in 0.12.0

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

# CVE-2026-29791 — agentgateway

MEDIUM [Fix: agentgateway/agentgateway@9a52875](https://github.com/agentgateway/agentgateway/commit/9a5287569d892e77a8be8c3bb7bf3d7744244274)

CVE-2026-29791 is a medium-severity (CVSS 4.9) Improper Input Validation vulnerability in github.com/agentgateway/agentgateway. A fix is available for github.com/agentgateway/agentgateway — see the affected versions and patch details below.

Agentgateway: Missing parameter sanitization in MCP to OpenAPI conversion

Also known as[GHSA-v2x6-wwfw-r2rq](/vulnerability/GHSA-v2x6-wwfw-r2rq)

Published

Mar 6, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

## Exploitation Status

### No confirmed exploitation observed yet

-   CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-29791.

## EPSS Exploitation Probability

[via FIRST.org ↗](https://www.first.org/epss/)

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs6th percentile — riskier than 6% of all scored CVEsHighest risk

0.00%0.25%0.49%0.74%0.1%0.2%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/).

## How urgent is this, really

## Where this sits among everything scored

## Real-World Exposure

1 pkg affected

🐹`github.com/agentgateway/agentgateway`

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

## Description

#### Summary

When converting MCP `tools/call` request to OpenAPI request, input path, query, and header values are not sanitized.

#### Details

When using the [MCP to OpenAPI](https://agentgateway.dev/docs/standalone/latest/mcp/connect/openapi/) feature, the proxy lacks proper sanitization of input parameters in the MCP call, allowing:

-   Injection of additional path or query parameters.
-   Injection of additional headers.

#### Impacted Versions

This vulnerability is fixed in Agentgateway v0.12.0+. Users on older versions are recommended to upgrade to v0.12.0+.

This feature only impacts usage of the [MCP to OpenAPI](https://agentgateway.dev/docs/standalone/latest/mcp/connect/openapi/) feature

#### Credits

Agentgateway extends its thanks to @spacewander for the report!

## Affected Packages

1 total 1 fixed

Ecosystem

Package

Vulnerable range

Fix

🐹Go

`github.com/agentgateway/agentgateway` 

all versions

0.12.0`go get github.com/agentgateway/agentgateway@v0.12.0`

## Affected Products

1 product · 1 configurations

Application

`agentgateway`lfprojects

< 0.12.0

range

## Detection & mitigation playbook

Open-source dependency

1.  ### Detect
    
    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/agentgateway/agentgateway, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
    
2.  ### Fix
    
    Update github.com/agentgateway/agentgateway to 0.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-29791 is resolved across your whole dependency graph.
    
3.  ### Workarounds
    
    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
    

## Frequently Asked Questions

\### Summary When converting MCP \`tools/call\` request to OpenAPI request, input path, query, and header values are not sanitized. ### Details When using the \[MCP to OpenAPI\](https://agentgateway.dev/docs/standalone/latest/mcp/connect/openapi/) feature, the proxy lacks proper sanitization of input parameters in the MCP call, allowing: \* Injection of additional path or query parameters. \* Injection of additional headers. ### Impacted Versions This vulnerability is fixed in Agentgateway v0.12.0+. Users on older versions are recommended to upgrade to v0.12.0+. This feature only impacts usage

O3 Security · Impact-Aware SCA

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