In plain language
What this advisory means
A problem in the AWS SDK for Go v2 can cause a program using it to crash if it receives a specially messed-up message. This happens because the program tries to read a part of the message called the EventStream header, but if the message contains an invalid type byte, the program will stop working unexpectedly.
Technical explanation
How the issue affects the environment
In AWS SDK for Go v2 versions before 2026-03-23, the EventStream header decoder does not properly validate the header value type byte. An attacker can send a malformed EventStream response frame with a crafted header value type byte that falls outside the valid range. This causes the decoder to process unexpected data, leading to termination of the host process, effectively a denial of service via improper input handling in the EventStream header decoding logic.
Operational impact
Why teams should care
This vulnerability can disrupt services running software based on the AWS SDK for Go v2 by causing application crashes. Denial of service incidents may reduce system availability and affect end-user experience, potentially causing operational interruptions and reputational damage for organizations relying on affected versions.
Immediate action
Upgrade to version 2026-03-23 or later of AWS SDK for Go v2 to resolve this issue. Ensure any forked or derivative code incorporates these updates.
Affected and fixed releases
Temporary risk reduction
The official bulletin states that no workarounds are applicable for this issue.
Evidence and validation checklist
- AWS Security Bulletin 2026-110-AWS published 2026-09-11
- Description of malformed EventStream header value type byte causing host process termination
- Resolution confirmed in versions 2026-03-23 and later
- No workarounds applicable
Authoritative reference
AWS Security Bulletins
QCS detected and normalized this record from the official source. Vendor guidance remains authoritative.