CVE-2026-109438

3proxy 0.9.7 - 1.0.1 Uninitialized Stack Memory Disclosure via SOCKS4

MEDIUM
5.3
CVSS Score
Published: October 14, 2026 at 03:53 PM UTC
Updated: October 27, 2026 at 01:30 AM UTC
1 product affected across 1 vendor3PROXY

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

0.9.7
Vendor states this is fixed in 206c923d6cd433bd2e7196375442650c328b8bfa (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-908

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