Medium 5.3Published May 7, 2026

CVE-2026-39819Invoking "go bug" follows symlinks in predictable temporary filenames in cmd/go

Updated under an hour ago (Oct 27, 2026, 11:00 AM 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 bug" command writes to two files with predictable names in the system temporary directory (for example, "/tmp"). An attacker with access to the temporary directory can create a symlink in one of these names, causing "go bug" to overwrite the target of the symlink.

CVSS: 5.3 MEDIUM (v3.1, CISA ADP)CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
Weakness (CWE): CWE-377
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/78584	issue-tracking
https://go.dev/cl/763882	patch
https://groups.google.com/g/golang-announce/c/qcCIEXso47M	issue-tracking, mailing-list
https://pkg.go.dev/vuln/GO-2026-4978	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.