Medium 5.9Published May 7, 2026

CVE-2026-39817Invoking "go tool pack" does not sanitize output paths in cmd/go

Updated under an hour ago (Oct 27, 2026, 2:30 PM ET)

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It affects Go toolchain cmd/go and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Go toolchain cmd/go

Exploited in the last 30 days

The "go tool pack" subcommand (usually used only by the compiler as an internal tool with known-good inputs) does not sanitize output filenames. Extracting a malicious archive file with the "pack" subcommand can write files to arbitrary locations on the filesystem.

CVSS: 5.9 MEDIUM (v3.1, CISA ADP)CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:N
Weakness (CWE): CWE-22
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Go
NVD analysis: Analyzed
Record last updated: May 8, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Go toolchain cmd/go go_toolchain:cmd_go (from the name)	before 1.25.10; from 1.26.0-0 before 1.26.3	CNA record
golang go golang:go	before 1.25.10; from 1.26.0 before 1.26.3	NVD

References

References

https://go.dev/issue/78778	issue-tracking
https://go.dev/cl/767520	patch
https://groups.google.com/g/golang-announce/c/qcCIEXso47M	issue-tracking, mailing-list
https://pkg.go.dev/vuln/GO-2026-4979	vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.