Vulnerability in 3proxy
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.
Published .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/3proxy/3proxy/commit/206c923d6cd433bd2e7196375442650c328b8bfa (issue-tracking, patch)
- www.vulncheck.com/advisories/3proxy-uninitialized-stack-memory-disclosure-via-s… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-109438?
- CVE-2026-109438 is a medium-severity vulnerability in 3proxy, classified under Use of Uninitialized Resource. CVSS score: 5.3/10. Published 2026-10-14.
- How severe is CVE-2026-109438?
- Medium severity. CVSS v3 base score is 5.3 out of 10.