High 7.5Published Aug 13, 2026

CVE-2026-56864Ignore unrelated, unauthenticated hashes in Lookup in golang.org/x/mod/sumdb

Updated under an hour ago (Oct 27, 2026, 1:23 PM ET)

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It affects Go toolchain cmd/go and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Go toolchain cmd/go

Exploited in the last 30 days

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

CVSS: 7.5 HIGH (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-347
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Go
NVD analysis: Awaiting Analysis
Record last updated: Aug 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Go toolchain cmd/go go_toolchain:cmd_go (from the name)	before 1.25.13; from 1.26.0-0 before 1.26.6; 1.27.0-0 builds before 1.27.0-rc.3	CNA record
golang.org/x/mod golang.org/x/mod/sumdb golang.org_x_mod:sumdb (from the name)	before 0.40.0	CNA record

References

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.