CVE-2026-39819 Invoking "go bug" follows symlinks in predictable temporary filenames in cmd/go
An attacker can overwrite arbitrary files via symlink attacks when the go bug command writes to predictable temporary filenames.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39819?
CVE-2026-39819 is a medium-severity path traversal vulnerability in Golang Go, published on 7 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-59
Which versions are affected by CVE-2026-39819?
2 open source packages ship an affected version, including golang and toolchain. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
golang Bitnami | All versions | 1.25.10, 1.26.3 |
toolchain Go | All versions | 1.25.10, 1.26.3 |
Products include Golang Go.
How do I fix CVE-2026-39819?
Upgrade golang to a fixed version for your release line: 1.25.10 or 1.26.3.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-39819 being exploited?
There is no known exploitation of CVE-2026-39819 in the wild and no public exploit code.
Other vulnerabilities in Golang Go
- CVE-2020-0601 Microsoft Windows CryptoAPI Spoofing
- CVE-2026-27143 Missing bound checks can lead to memory corruption in safe Go in cmd/compile
- CVE-2024-24790 Unexpected behavior from Is methods for IPv4-mapped IPv6 addresses in net/netip
- CVE-2023-39320 Arbitrary code execution via go.mod toolchain directive in cmd/go
- CVE-2023-24540 Improper handling of JavaScript whitespace in html/template
Sources
Also known as AZL-98826, BELL-CVE-2026-39819, BIT-golang-2026-39819, CLEANSTART-2026-NT43393, CLEANSTART-2026-VA36880, CLEANSTART-2026-WS35873 and 790 more.