CVE-2026-33811: Golang Go

High severity, CVSS 7.5. EPSS: 0.8% chance of exploitation in the next 30 days.

When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a crash.

Affected products

• Golang Go: before 1.25.10 (fixed in 1.25.10); from 1.26.0, before 1.26.3 (fixed in 1.26.3)

Published 2026-05-07. Last modified 2026-09-18.