CVE-2026-56864

Summary

A malicious GOSUMDB was capable of serving arbitrary module content not contained within the transparency log. This attack allows for a coordinating GOPROXY and GOSUMDB to serve a client malicious module content that cannot be detected by evaluating the transparency log. In order to determine if you have been affected: rm -r go.sum go.work.sum vendor/ && go mod tidy

Affected Software

VendorProductVersion RangeStatus
Go toolchaincmd/go0 < 1.25.13affected
Go toolchaincmd/go1.26.0-0 < 1.26.6affected
Go toolchaincmd/go1.27.0-0 < 1.27.0-rc.3affected
golang.org/x/modgolang.org/x/mod/sumdb0 < 0.40.0affected

Weaknesses

  • CWE-347: Improper Verification of Cryptographic Signature

References