Bug 2552572 (CVE-2026-109438)

Summary: CVE-2026-109438 3proxy: 3proxy: Information disclosure via uninitialized stack memory in SOCKS reply
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in 3proxy. When configured with external network address translation (NAT), a remote, unauthenticated attacker can trigger an information disclosure vulnerability by sending a crafted client probe that fails the SOCKS protocol version check. This causes the service to return a reply containing uninitialized stack memory, leaking internal memory pointers that can weaken Address Space Layout Randomization (ASLR) protections.
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Bug Depends On: 2553106, 2553107    
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Description OSIDB Bzimport 2026-10-14 17:22:52 UTC
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.