CVE-2026-39824

String truncation via unchecked 16-bit length conversion

Published May 22, 2026 · Updated May 22, 2026

Integer overflow in NewNTUnicodeString in golang.org/x/sys/windows before 0.44.0 allows local users to cause string truncation. The routine converts an oversized Go string to UTF-16, then narrows its byte count into 16-bit Length and MaximumLength fields without rejecting overflow, so the returned NTUnicodeString describes only a truncated prefix. Reachability requires a Windows application to pass more than the 16-bit byte capacity into this helper; the resulting truncation can alter data interpreted by a native NT API.

CVSS severity3.3
Low
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in NewNTUnicodeString in golang.org/x/sys/windows before 0.44.0 allows local users to cause string truncation. The routine converts an oversized Go string to UTF-16, then narrows its byte count into 16-bit Length and MaximumLength fields without rejecting overflow, so the returned NTUnicodeString describes only a truncated prefix. Reachability requires a Windows application to pass more than the 16-bit byte capacity into this helper; the resulting truncation can alter data interpreted by a native NT API.

The record

CVE
CVE-2026-39824
Published
May 22, 2026
Updated
May 22, 2026
Vendor
golang.org/x/sys
Product
golang.org/x/sys/windows
Classifications
CWE-190
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. May 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.44.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

golang.org/x/sys · golang.org/x/sys/windowsversion=0 <0.44.0

Published CVSS scores

3.3CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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