CVE-2026-109438 3proxy 0.9.7 - 1.0.1 Uninitialized Stack Memory Disclosure via SOCKS4
Unauthenticated attackers can leak stack memory via SOCKS4 replies when external-NAT is enabled, weakening ASLR protections in 3proxy.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-109438?
CVE-2026-109438 is a medium-severity vulnerability in 3proxy, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-908
Which versions are affected by CVE-2026-109438?
How do I fix CVE-2026-109438?
No fix has been published for CVE-2026-109438 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-109438 being exploited?
There is no known exploitation of CVE-2026-109438 in the wild and no public exploit code.
Sources
Also known as GHSA-4226-q7gw-49h8.