CVE-2026-39819

Description

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 Metrics

• v3.1•MEDIUM•Score: 5.3CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N

EPSS Trends

Current EPSS score: 0.01%• Percentile: 1%

Techniques & Countermeasures

• CWE-59•Improper Link Resolution Before File Access ('Link Following')

  The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Systems

• go toolchain•cmd/go

  < 1.25.10 | ≥ 1.26.0-0, < 1.26.3

• golang•go

  < 1.25.10 | ≥ 1.26.0, < 1.26.3

• Go•toolchain

  ≥ 1.26.0-0, < 1.26.3

References (4)

• https://go.dev/issue/78584
• https://go.dev/cl/763882
• https://groups.google.com/g/golang-announce/c/qcCIEXso47M
• https://pkg.go.dev/vuln/GO-2026-4978