CVE-2026-56864

UNKNOWN 0.0

Ignore unrelated, unauthenticated hashes in Lookup in golang.org/x/mod/sumdb

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

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

Vendor	go toolchain
Product	cmd/go
Published	Aug 13, 2026

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Affected Versions

Go toolchain / cmd/go

0 < 1.25.13 1.26.0-0 < 1.26.6 1.27.0-0 < 1.27.0-rc.3

golang.org/x/mod / golang.org/x/mod/sumdb

0 < 0.40.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

go.dev: https://go.dev/issue/80745 groups.google.com: https://groups.google.com/g/golang-announce/c/94pEornpRlI go.dev: https://go.dev/cl/815000 go.dev: https://go.dev/cl/815020 pkg.go.dev: https://pkg.go.dev/vuln/GO-2026-6180

Credits

mundur