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
Published: 2026-08-13
Score: 8.4 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Fri, 14 Aug 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 8.4, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Fri, 14 Aug 2026 13:00:00 +0000

Type Values Removed Values Added
First Time appeared Golang
Golang mod
Gotoolchain
Gotoolchain cmd/go
Vendors & Products Golang
Golang mod
Gotoolchain
Gotoolchain cmd/go

Fri, 14 Aug 2026 01:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-347

Thu, 13 Aug 2026 22:15:00 +0000

Type Values Removed Values Added
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
Title Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Go

Published:

Updated: 2026-08-14T15:34:17.235Z

Reserved: 2026-06-23T15:10:49.354Z

Link: CVE-2026-56865

cve-icon Vulnrichment

Updated: 2026-08-14T15:34:11.473Z

cve-icon NVD

Status : Received

Published: 2026-08-13T22:17:22.797

Modified: 2026-08-14T16:16:57.860

Link: CVE-2026-56865

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-14T18:45:17Z

Weaknesses