CVE-2026-39817: Go toolchain cmd/go · Path Traversal
Affects Go toolchain cmd/goSource CVE Database V5
Not known to be exploited · CVSS 5.9 Medium : upgrade to 1.26.3 or 1.25.10 when convenient.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% 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:L/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:NExploitation 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
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, users should exercise caution when extracting archives with the 'go tool pack' subcommand, especially from untrusted sources. Avoid processing untrusted archives to mitigate risk.
Description
CVE-2026-39817 is a medium-severity path traversal vulnerability in the Go toolchain's cmd/go component, specifically affecting the 'go tool pack' subcommand. This flaw allows a malicious archive to write files to arbitrary filesystem locations due to improper sanitization of output filenames when extracting archives. It affects Go versions up to 1.26.0-0.