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Vulnerability record · CVE-2026-56864 · published 13 August 2026

CVE-2026-56864: Improper verification of cryptographic signature vulnerability

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

7.5 CVSS 3.1 High EPSS 0.32% · top 78.0% CWE-347 · Improper verification of cryptographic signature Undergoing Analysis
7.5CVSS 3.1 base score
0.32%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
5References
3 Sep 2026Last modified by NVD

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

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

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Source: NIST National Vulnerability Database (record CVE-2026-56864), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.