Bug 2570318 (CVE-2026-125371)

Summary: CVE-2026-125371 tinyproxy: Tinyproxy: Access control bypass via improper hostname matching
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 Tinyproxy. The proxy server improperly validates client hostnames against access control lists (ACLs) by matching trailing characters without verifying Domain Name System (DNS) label boundaries. A remote attacker who controls reverse DNS pointer (PTR) records for their IP address can craft a hostname that matches the end of an allowed domain, bypassing access restrictions to unauthorizedly route traffic through the proxy.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2572404, 2572406    
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Description OSIDB Bzimport 2026-11-10 19:50:39 UTC
Tinyproxy through 1.11.3 contains an access control bypass vulnerability in acl_string_processing() in src/acl.c that compares only trailing hostname characters without checking DNS label boundaries. Attackers controlling the PTR record for their source IP, such as untrusted.net, can satisfy an 'Allow trusted.net' entry to use the proxy despite deny-by-default ACLs.