Vulnerability in Go standard library crypto/tls

[ Description ]Official description

Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund8 Oct 2026WID-SEC-2026-3841

  Golang Go: Multiple vulnerabilities Translated from German

  Risk mediumCVE-2026-94439CVE-2026-56866CVE-2026-94447+12 more CVEs

[ References ]References

• go.dev/cl/847312
• go.dev/issue/81855
• groups.google.com/g/golang-announce/c/U2fTuyDJznI
• pkg.go.dev/vuln/GO-2026-6607