CVE-2022-23959 in Cache
Summary
by MITRE • 01/26/2022
In Varnish Cache before 6.6.2 and 7.x before 7.0.2, Varnish Cache 6.0 LTS before 6.0.10, and and Varnish Enterprise (Cache Plus) 4.1.x before 4.1.11r6 and 6.0.x before 6.0.9r4, request smuggling can occur for HTTP/1 connections.
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Analysis
by VulDB Data Team • 11/15/2024
The vulnerability identified as CVE-2022-23959 represents a critical HTTP request smuggling flaw affecting multiple versions of Varnish Cache and its enterprise variant. This vulnerability specifically targets HTTP/1 connections and arises from improper handling of request parsing and forwarding mechanisms within the caching system. The issue allows malicious actors to manipulate HTTP requests in ways that can bypass security controls and potentially access unauthorized resources. The vulnerability affects both the long-term support version 6.0 and the newer 6.x series, as well as the enterprise Cache Plus variant, indicating a widespread impact across different Varnish Cache deployments.
The technical flaw stems from inadequate validation of HTTP request boundaries and connection handling when processing HTTP/1.1 requests through the Varnish Cache proxy. This weakness creates opportunities for request smuggling attacks where an attacker can craft malicious requests that appear legitimate to the frontend server but contain unexpected content that gets interpreted differently by the backend systems. The vulnerability manifests when Varnish Cache fails to properly separate and validate individual HTTP requests within a single connection, allowing for the injection of additional requests or modification of existing request parameters. This behavior aligns with CWE-444, which describes improper request routing or parsing issues in web applications and proxies.
The operational impact of this vulnerability extends beyond simple caching performance degradation, as it can enable serious security breaches including unauthorized data access, privilege escalation, and potential system compromise. Attackers could exploit this vulnerability to bypass authentication mechanisms, access protected resources, or perform actions on behalf of other users. The vulnerability is particularly dangerous in environments where Varnish Cache serves as a front-end proxy for sensitive applications or where it handles requests from untrusted sources. Organizations relying on Varnish Cache for web application delivery face significant risk exposure, especially when the cache serves as a critical component in their security architecture.
Mitigation strategies for CVE-2022-23959 require immediate deployment of patched versions of Varnish Cache and its enterprise variants. System administrators should upgrade to Varnish Cache 6.6.2 or later, 7.0.2 or later, Varnish Cache 6.0.10 or later, Varnish Enterprise Cache Plus 4.1.11r6 or later, and Varnish Enterprise Cache Plus 6.0.9r4 or later. Additionally, organizations should implement network-level monitoring to detect anomalous HTTP request patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper HTTP protocol compliance in proxy implementations and highlights the need for thorough testing of connection handling mechanisms. Security teams should also consider implementing additional layers of protection such as web application firewalls and request validation rules to reduce the attack surface and provide defense-in-depth measures against similar vulnerabilities. This issue aligns with ATT&CK technique T1190, which covers exploiting vulnerabilities in web applications and proxy services, emphasizing the need for comprehensive vulnerability management and patch deployment processes.