CVE-2026-56864: CWE-347: Improper Verification of Cryptographic Signature in Go toolchain cmd/go
CVE-2026-56864 is a vulnerability in the Go toolchain's cmd/go component involving improper verification of cryptographic signatures. A malicious GOSUMDB server can serve arbitrary module content that is not recorded in the transparency log, enabling coordinated GOPROXY and GOSUMDB servers to deliver undetectable malicious modules to clients. The vulnerability affects multiple versions of the Go toolchain. No official patch or remediation guidance is currently available. Users can check if they have been affected by removing certain module files and running 'go mod tidy'.
AI Analysis
Technical Summary
This vulnerability (CWE-347) in the Go toolchain's cmd/go allows a malicious GOSUMDB to serve arbitrary module content that bypasses the transparency log verification. This enables an attacker controlling both GOPROXY and GOSUMDB to deliver malicious modules to clients without detection by the transparency log. The affected versions include =1.26.0-0, =1.27.0-0, <1.25.13, >=1.26.0-0 <1.26.6, and <0.40.0. There is no CVSS score or official remediation level published yet.
Potential Impact
Clients using affected versions of the Go toolchain may receive malicious module content that is not recorded in the transparency log, potentially leading to supply chain compromise. The attack requires control of both GOPROXY and GOSUMDB to coordinate delivery of malicious modules undetectable by normal verification mechanisms.
Mitigation Recommendations
No official patch or remediation is currently documented. Users are advised to check if they have been affected by removing go.sum, go.work.sum, and vendor/ directories and then running 'go mod tidy' to refresh module dependencies. Monitor vendor advisories for updates and patches.
CVE-2026-56864: CWE-347: Improper Verification of Cryptographic Signature in Go toolchain cmd/go
Description
CVE-2026-56864 is a vulnerability in the Go toolchain's cmd/go component involving improper verification of cryptographic signatures. A malicious GOSUMDB server can serve arbitrary module content that is not recorded in the transparency log, enabling coordinated GOPROXY and GOSUMDB servers to deliver undetectable malicious modules to clients. The vulnerability affects multiple versions of the Go toolchain. No official patch or remediation guidance is currently available. Users can check if they have been affected by removing certain module files and running 'go mod tidy'.
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CWE-347) in the Go toolchain's cmd/go allows a malicious GOSUMDB to serve arbitrary module content that bypasses the transparency log verification. This enables an attacker controlling both GOPROXY and GOSUMDB to deliver malicious modules to clients without detection by the transparency log. The affected versions include =1.26.0-0, =1.27.0-0, <1.25.13, >=1.26.0-0 <1.26.6, and <0.40.0. There is no CVSS score or official remediation level published yet.
Potential Impact
Clients using affected versions of the Go toolchain may receive malicious module content that is not recorded in the transparency log, potentially leading to supply chain compromise. The attack requires control of both GOPROXY and GOSUMDB to coordinate delivery of malicious modules undetectable by normal verification mechanisms.
Mitigation Recommendations
No official patch or remediation is currently documented. Users are advised to check if they have been affected by removing go.sum, go.work.sum, and vendor/ directories and then running 'go mod tidy' to refresh module dependencies. Monitor vendor advisories for updates and patches.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Go
- Date Reserved
- 2026-06-23T15:10:49.354Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a7e412ebf8831d539e05137
Added to database: 08/13/2026, 22:11:58 UTC
Last enriched: 08/13/2026, 22:27:27 UTC
Last updated: 08/14/2026, 01:52:06 UTC
Views: 6
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