Go cmd/go Checksum Bypass (Go <1.26.9, 1.27.0-1.27.2)
CVE-2026-94447 Published on October 8, 2026
Checksum database bypass for golang.org/toolchain in cmd/go
Previously, a user operating inside of a malicious Go project that defines a bogus golang.org/toolchain go.sum entry and operates a malicious GOMODPROXY the user chooses to use can bypass the intended checksum. We now ensure that golang.org/toolchain always goes to the network for the canonical checksum.
Vulnerability Analysis
CVE-2026-94447 can be exploited with local system access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
Improper Validation of Integrity Check Value
The software does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission. Improper validation of checksums before use results in an unnecessary risk that can easily be mitigated. The protocol specification describes the algorithm used for calculating the checksum. It is then a simple matter of implementing the calculation and verifying that the calculated checksum and the received checksum match. Improper verification of the calculated checksum and the received checksum can lead to far greater consequences.
Products Associated with CVE-2026-94447
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Affected Versions
Go toolchain cmd/go:- Before 1.26.9 is affected.
- Version 1.27.0-0 and below 1.27.2 is affected.