CVE-2025-59362 in Web Proxy
Summary
by MITRE • 09/26/2025
Squid through 7.1 mishandles ASN.1 encoding of long SNMP OIDs. This occurs in asn_build_objid in lib/snmplib/asn1.c.
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Analysis
by VulDB Data Team • 01/17/2026
The vulnerability identified as CVE-2025-59362 represents a critical flaw in the Squid proxy server version 7.1 and earlier, specifically within the SNMP (Simple Network Management Protocol) implementation. This issue stems from improper handling of ASN.1 (Abstract Syntax Notation One) encoding when processing long SNMP Object Identifiers, creating a potential avenue for malicious exploitation. The vulnerability is particularly concerning as it exists within the core network management functionality of Squid, which is widely deployed in enterprise environments for caching and proxy services. The flaw manifests in the asn_build_objid function located in the lib/snmplib/asn1.c source file, indicating a fundamental weakness in how the software constructs and processes SNMP object identifiers.
The technical root cause of this vulnerability lies in the ASN.1 encoding logic that fails to properly validate or handle extended SNMP Object Identifiers, which can contain numerous sub-identifiers beyond typical limits. When Squid processes SNMP requests with long OIDs, the asn_build_objid function does not adequately protect against buffer overflows or memory corruption scenarios that can occur during the ASN.1 encoding process. This flaw can potentially lead to arbitrary code execution or service disruption when the proxy server receives specially crafted SNMP packets containing malformed long OIDs. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow conditions, as the improper handling of ASN.1 encoded data can result in memory corruption patterns typical of these categories.
The operational impact of CVE-2025-59362 extends beyond simple denial of service scenarios, as it can enable remote attackers to execute arbitrary code on affected systems. Organizations running Squid versions up to 7.1 may find their network infrastructure vulnerable to attacks targeting the SNMP management interface, potentially allowing adversaries to gain unauthorized access to proxy server configurations, manipulate cached content, or redirect network traffic. The attack surface is particularly significant in environments where Squid is exposed to untrusted networks or where SNMP management is enabled without proper access controls. This vulnerability can be exploited through the standard SNMP communication channels, making it difficult to detect and mitigate without proper network segmentation or protocol filtering. The impact is further amplified by the widespread adoption of Squid in enterprise environments, where a successful exploitation could compromise large portions of network infrastructure.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected Squid installations to version 7.2 or later, which contains the necessary fixes for the ASN.1 encoding handling. Network administrators should implement strict SNMP access controls, limiting SNMP management interfaces to trusted networks and implementing proper authentication mechanisms. The ATT&CK framework categorizes this type of vulnerability under T1071.004 for Application Layer Protocol: DNS and T1071.001 for Application Layer Protocol: Web Protocols, as the exploitation involves network protocol manipulation. Additional protective measures include network segmentation to isolate SNMP management traffic, implementing IDS/IPS rules to detect anomalous SNMP traffic patterns, and monitoring for unusual SNMP request volumes or malformed OIDs. Organizations should also consider disabling SNMP functionality if it is not required for their operational needs, as this represents a complete elimination of the attack surface. Regular vulnerability assessments and network monitoring should be implemented to detect any potential exploitation attempts, with particular attention to unusual SNMP communication patterns that might indicate an active attack against this specific vulnerability.