Upgrade Go to 1.26.4 to address GO-2026-5037 (quadratic-time DoS in crypto/x509 VerifyHostname with large DNS SAN lists, CVE-2026-27145) and GO-2026-5039 (error message injection in net/textproto, CVE-2026-42507).
Full Changelog: v6.2.7...v6.2.8