CVE-2026-56865

high

Description

A malicious GOPROXY was previously capable of forging up to two sumdb tiles that allow for a requested module to bypass the GOSUMDB check and persist attacker-controlled module content to a local Go module cache. This attack allows for a malicious GOPROXY to serve malicious module content that cannot be detected by evaluating the transparency log. All tiles are now correctly verified against their parents. In order to determine if you have been affected: rm -r go.sum go.work.sum vendor/ && go mod tidy

References

https://pkg.go.dev/vuln/GO-2026-6179

https://groups.google.com/g/golang-announce/c/94pEornpRlI

https://go.dev/issue/80744

https://go.dev/cl/815020

https://go.dev/cl/814960

Details

Source: Mitre, NVD

Published: 2026-08-13

Updated: 2026-08-14

Risk Information

CVSS v2

Base Score: 7.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 8.4

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

Severity: High

EPSS

EPSS: 0.00123