Double Free in Golang Go
CVE-2026-33811
When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a crash.
Vulnerability class: Double Free
EPSS: 0.000 (4.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Golang Go
- Go Standard Library Net — versions 0, 1.26.0-0
Weakness classification (CWE)
References
- security@golang.org (Issue Tracking)
- security@golang.org (Patch)
- security@golang.org (Mailing List, Third Party Advisory)
- security@golang.org (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-33811?
- CVE-2026-33811 is a high-severity vulnerability in Golang Go, classified under Double Free. CVSS score: 7.5/10. Published 2026-05-07.
- How severe is CVE-2026-33811?
- High severity. CVSS v3 base score is 7.5 out of 10.