---
id: "CVE-2026-89090"
kind: "vulnerability"
aliases: ["CVE-2026-89090"]
title: "AWS SDK for Go v2: malformed event stream frame crashes host process"
severity: "high"
cvss: 8.2
epss: 0.00305
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["aws", "aws-sdk-go-v2", "go", "lab-disclosure", "package"]
not_affected_if: ["release-2026-03-23-or-later"]
published_at: "2026-09-11T18:17:00+00:00"
first_seen_at: "2026-10-24T18:43:45+00:00"
updated_at: "2026-10-25T12:38:49+00:00"
sources: [{"source": "lab", "url": "https://aws.amazon.com/security/security-bulletins/rss/2026-110-aws/", "first_seen_at": "2026-10-24T18:43:45+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89090", "first_seen_at": "2026-10-24T18:53:56+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-89090", "first_seen_at": "2026-10-25T12:38:49+00:00"}]
---

# AWS SDK for Go v2: malformed event stream frame crashes host process

The AWS SDK for Go v2 event stream header decoder does not recover from a panic when it receives a crafted header value type byte outside the valid range. An attacker who can send a malformed EventStream response frame can terminate the host process, causing denial of service.

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

## How to check

- Check the SDK version in `go.mod` for `github.com/aws/aws-sdk-go-v2` and related service modules, and compare against `2026-03-23`
- Look for code that consumes EventStream responses (for example Transcribe streaming, S3 Select, or Kinesis subscribe-to-shard) and confirm which modules are in use

## Fix

- Upgrade the AWS SDK for Go v2 to release `2026-03-23` or later
- Patch any forked or vendored copies of the event stream decoder to include the upstream fix

## Timeline

- 2026-10-24T18:43:45+00:00 lab https://aws.amazon.com/security/security-bulletins/rss/2026-110-aws/ — AWS: CVE-2026-89090 - Denial of service in the event stream header decoder in AWS SDK for Go v2
- 2026-10-24T18:53:56+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-89090
- 2026-10-25T12:38:49+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-89090

## Documents

- [advisory] AWS: CVE-2026-89090 - Denial of service in the event stream header decoder in AWS SDK for Go v2 https://aws.amazon.com/security/security-bulletins/rss/2026-110-aws/

## From the sources

CVE-2026-89090 - Denial of service in the event stream header decoder in AWS SDK for Go v2

### CVE-2026-89090 - Denial of service in the event stream header decoder in AWS SDK for Go v2

Bulletin ID: 2026-110-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 09/11/2026 10:00 AM PDT

Description:

An issue exists in the the EventStream header decoder in AWS SDK for Go v2 in versions predating 2026-03-23. An actor can send a malformed EventStream response frame containing a crafted header value type byte outside the valid range, which can cause the host process to terminate.

Impacted versions: < 2026-03-23

Resolution:

This issue has been addressed in versions 2026-03-23 and above. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

Workarounds:

Not applicable.

References:

- CVE-2026-89090
- GHSA-xmrv-pmrh-hhx2

 Please email aws-security@amazon.com with any security questions or concerns.

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