Vulnerability/
https://seclists.org/oss-sec/2026/q4/646

https://seclists.org/oss-sec/2026/q4/646: Go 1.27.4 and Go 1.26.11 are released with 12 security fixes

Q: How can I determine whether an HTTP/1 service is exposed to the server crash?

The crash condition applies to HTTP/1 servers that use MaxBytesReader or MaxBytesHandler and have a handler that reads the request body concurrently with writing the response header. The issue is triggered when the MaxBytesReader limit is exceeded and the connection-close header races with another header update.

Q: What would an attacker need to do to exploit the cgo-related issue?

The issue involves building a malicious package that uses cgo. The announcement states that this can cause arbitrary code execution through cgo-related compiler and linker flags, including --sysroot, -target, -isysroot, -Wl,-syslibroot, and -x.

Published Nov 10, 2026

Updated

Affected Software

1 affected component

Google Go>=1.26.0<=1.26.10, >=1.27.0<=1.27.3

Frequently Asked Questions

How can I determine whether an HTTP/1 service is exposed to the server crash?

The crash condition applies to HTTP/1 servers that use MaxBytesReader or MaxBytesHandler and have a handler that reads the request body concurrently with writing the response header. The issue is triggered when the MaxBytesReader limit is exceeded and the connection-close header races with another header update.

What would an attacker need to do to exploit the cgo-related issue?

The issue involves building a malicious package that uses cgo. The announcement states that this can cause arbitrary code execution through cgo-related compiler and linker flags, including --sysroot, -target, -isysroot, -Wl,-syslibroot, and -x.

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