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CVE-2026-109438

MEDIUMCVSS 5.3/10

Last modified

CVE-2026-109438 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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..

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.

Metrics

CVSS 3.1
5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS 4.0
6.3/10

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
3proxy3proxy>= 0.9.7, <= 1.0.1

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-109438?
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.
How severe is CVE-2026-109438?
CVE-2026-109438 has a CVSS score of 5.3/10 (MEDIUM severity).
How do I fix CVE-2026-109438?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST