Vulnerability 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
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://go.dev/cl/814960
- https://go.dev/cl/815020
- https://go.dev/issue/80744
- https://groups.google.com/g/golang-announce/c/94pEornpRlI
- https://pkg.go.dev/vuln/GO-2026-6179
FAQ
What is CVE-2026-56865?
CVE-2026-56865 is a vulnerability with a CVSS score of 8.4 (HIGH). 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 m...
How severe is CVE-2026-56865?
CVE-2026-56865 has been rated HIGH with a CVSS base score of 8.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-56865?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.