---
id: CVE-2026-109438
title: >-
  3proxy from 0.9.7 through 1.0.1, fixed in commit 206c923, contains an
  uninitialized stack memory disclosure vulnerability that allows
  unauthenticated attackers to leak stack bytes via the SOCKS4 reply path when
  the external-NAT option (-…
summary: >-
  3proxy from 0.9.7 through 1.0.1, fixed in commit 206c923, contains an
  uninitialized stack memory disclosure vulnerability that allows
  unauthenticated attackers to leak stack bytes via the SOCKS4 reply path when
  the external-NAT option (-…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-908
published: '2026-10-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T16:17:36.783'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109438'
references:
  - url: >-
      https://github.com/3proxy/3proxy/commit/206c923d6cd433bd2e7196375442650c328b8bfa
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/3proxy-uninitialized-stack-memory-disclosure-via-socks4
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-10-14T16:40:32.112Z'
---

## Overview

3proxy from 0.9.7 through 1.0.1, fixed in commit 206c923, contains an uninitialized stack memory disclosure vulnerability that allows unauthenticated attackers to leak stack bytes via the SOCKS4 reply path when the external-NAT option (-Ne) is configured. Attackers can send a client probe that fails the SOCKS version check to trigger a reply containing uninitialized bytes from the sin structure, exposing high bytes of a userspace pointer that weakens ASLR protections.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.