Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Go toolchain versions before 1.25.10 and from 1.26.0 up to (but not including) 1.26.3 are affected. An attacker running a malicious module proxy (GOPROXY) can serve altered Go toolchains or modules, and the go command can accept them by bypassing checksum database validation, so users of an untrusted proxy may run attacker-supplied code. Upgrade to Go 1.25.10 or 1.26.3; setting GOTOOLCHAIN to a fixed version is not sufficient.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 7.5 | High | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H | ADP (CISA-ADP) |
- CISA KEV Not listed.
- EPSS 0.0023, the 14th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 7 May 2026, 20:16 UTC Confirmed by NVD
- 31 Oct 2026, 14:48 UTC First seen by agentprime
- 31 Oct 2026, 14:48 UTC Confirmed by OSV