CVE-2026-56864

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

State: Published
Severity: 7.5 High
Published: Aug 13, 2026
Updated: Aug 14, 2026
Reserved: Jun 23, 2026

Description

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

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N	CISA-ADP

Weaknesses

CWE-347 Improper Verification of Cryptographic Signature

Affected Products

Product	Versions
cmd/goGo toolchain	before 1.25.13Affected 1.26.0-0 to before 1.26.6Affected 1.27.0-0 to before 1.27.0-rc.3Affected
golang.org/x/mod/sumdbgolang.org/x/mod	before 0.40.0Affected

References

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