CVE-2026-39836 Panic in Dial and LookupPort when handling NUL byte on Windows in net
Attackers can cause a denial of service by triggering a panic in Go's net package on Windows via NUL bytes in Dial or LookupPort inputs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39836?
CVE-2026-39836 is a high-severity vulnerability in Golang Go, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The Dial and LookupPort functions panic on Windows when provided with an input containing a NUL (0).
Weakness: CWE-476
Which versions are affected by CVE-2026-39836?
2 open source packages ship an affected version, including golang and stdlib. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
golang Bitnami | All versions | 1.25.10, 1.26.3 |
stdlib Go | All versions | 1.25.10, 1.26.3 |
Products include Golang Go.
How do I fix CVE-2026-39836?
Upgrade golang to a fixed version for your release line: 1.25.10 or 1.26.3.
Is CVE-2026-39836 being exploited?
There is no known exploitation of CVE-2026-39836 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-98619, BELL-CVE-2026-39836, BIT-golang-2026-39836, CLEANSTART-2026-EW49412, CLEANSTART-2026-FK79056, CLEANSTART-2026-GL68033 and 804 more.