CVE-2026-39824: Invoking integer overflow in NewNTUnicodeString in golang.org/x/sys/windows

Severity: low (CVSS 3.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-22 · updated 2026-07-23
Weakness: CWE-190

Description

NewNTUnicodeString does not check for string length overflow. When provided with a string that overflows the maximum size of a NTUnicodeString (a 16-bit number of bytes), it returns a truncated string rather than an error.

Affected products

Golang.Org/X/Sys: before 0.44.0 — fixed in 0.44.0
golang.org/x/sys/windows: before 0.44.0 — fixed in 0.44.0

How to fix

Upgrade to a fixed version: Golang.Org/X/Sys 0.44.0; golang.org/x/sys/windows 0.44.0. Check the vendor advisory for mitigations.

References

https://go.dev/cl/770080
https://go.dev/issue/78916
https://groups.google.com/g/golang-announce/c/6MMI8Lj-Atg
https://pkg.go.dev/vuln/GO-2026-5024

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