Vulnerability in Go toolchain cmd/go

[ Description ]Official description

Previously, a user operating inside of a malicious Go project that defines a bogus golang.org/fips140 and operates a malicious GOMODPROXY the user chooses to connect to can serve an arbitrary module in its place. We now unpack the trusted ziphash for the bundled golang.org/fips140 module and construct its entry in the GOMODCACHE such that it can be verified by the toolchain.

[ 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/840685
• go.dev/issue/81833
• groups.google.com/g/golang-announce/c/U2fTuyDJznI
• pkg.go.dev/vuln/GO-2026-6601