---
id: "CVE-2026-120235"
kind: "vulnerability"
aliases: ["CVE-2026-120235"]
title: "AG-UI protocol SSE parser lets remote input exhaust client resources"
severity: "medium"
cvss: 4.3
epss: null
exploited: false
status: "open"
category: "ai-tooling"
products: []
ecosystems: []
tags: ["ag-ui", "ai-agents", "ai-tooling", "sse", "typescript"]
not_affected_if: ["not-using-ag-ui-client"]
published_at: "2026-11-01T16:18:14+00:00"
first_seen_at: "2026-11-01T16:20:45+00:00"
updated_at: "2026-11-01T16:22:46+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-120235", "first_seen_at": "2026-11-01T16:20:45+00:00"}]
---

# AG-UI protocol SSE parser lets remote input exhaust client resources

The AG-UI protocol TypeScript client parses server-sent event streams in a way that a crafted stream can make consume excessive resources. An attacker who can send such a stream to the client can degrade or stall the application using it.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Look for the `ag-ui-protocol` or `@ag-ui/client` package in `package.json` and lockfiles, and check the installed version.
- Confirm whether the affected `parseSSEStream` code path in `sdks/typescript/packages/client/src/transform/sse.ts` is in use.

## Fix

- ag-ui up to `0.0.58`: upgrade to a later release; the sources name patch commit `9e7b2b00bce215bbf731f1e6094f63812527c432` but do not state the fixed version number.

## Timeline

- 2026-11-01T16:20:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-120235

## From the sources

A security vulnerability has been detected in ag-ui-protocol ag-ui up to 0.0.58. Affected is the function parseSSEStream of the file sdks/typescript/packages/client/src/transform/sse.ts of the component SSE Parser. The manipulation leads to resource consumption. The attack may be initiated remotely. The exploit has been disclosed publicly and may be used. The identifier of the patch is 9e7b2b00bce215bbf731f1e6094f63812527c432. The affected component should be upgraded.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_