CVE-2026-42501: Go toolchain cmd/go · Improper Verification of Cryptographic Signature
Affects Go toolchain cmd/goSource CVE Database V5
Not known to be exploited · CVSS 7.5 High : upgrade to 1.26.3 or 1.25.10 soon.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.26.3, 1.25.10
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 7 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade Go toolchain cmd/go to 1.26.3 or 1.25.10.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Go toolchaincmd/go | Affected
| Fixed in
|
| Go toolchaincmd/go | Affected
| Fixed in
|
Gocmd/gopkg:golang/cmd/goOther threats | Affected
| Fixed in
|
Gogithub.com/golang/go/cmd/gopkg:golang/github.com/golang/go/cmd/goOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
In the meantime, users should avoid using untrusted GOPROXY or GOSUMDB configurations. Potential compromise can be detected by regenerating and verifying go.sum files. No other vendor-provided mitigations are currently documented.
Description
CVE-2026-42501 is a high-severity vulnerability in the Go toolchain's cmd/go module handling that allows a malicious module proxy to bypass checksum database validation due to improper verification of cryptographic signatures. This flaw enables acceptance of empty or unrelated checksum responses as valid, potentially leading to execution of altered Go toolchain versions or modules when using untrusted GOPROXY or GOSUMDB configurations. No known exploits have been reported in the wild at this time.