CVE-2023-49285 in Squid
Summary
by MITRE • 12/05/2023
Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Due to a Buffer Overread bug Squid is vulnerable to a Denial of Service attack against Squid HTTP Message processing. This bug is fixed by Squid version 6.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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Analysis
by VulDB Data Team • 05/16/2025
The vulnerability identified as CVE-2023-49285 represents a critical buffer overread condition within the Squid caching proxy software that specifically affects HTTP message processing operations. This flaw exists within the software's handling of incoming HTTP requests and responses, where insufficient bounds checking allows an attacker to craft malicious HTTP messages that trigger memory access violations. The vulnerability manifests when Squid processes malformed or specially crafted HTTP content that exceeds expected buffer boundaries, causing the application to read beyond allocated memory regions. This type of flaw falls under the CWE-129 category of Improper Validation of Array Index, which directly relates to buffer overread conditions that can lead to unpredictable behavior and system instability. The attack vector requires minimal privileges and can be executed through standard HTTP communication channels, making it particularly dangerous for web infrastructure services that rely on Squid for caching and proxy operations.
The technical implementation of this vulnerability stems from inadequate input validation within Squid's HTTP message parsing routines. When processing HTTP requests or responses, the software fails to properly verify the length and structure of incoming data before attempting to read from memory buffers. This overread condition occurs during the parsing of HTTP headers or content bodies where the application attempts to access memory locations beyond the allocated buffer space. The flaw is particularly concerning because it can be triggered by any HTTP message that contains malformed data structures, potentially including crafted headers, content encoding issues, or unexpected payload characteristics. From an operational perspective, this vulnerability creates a reliable path for denial of service attacks that can bring down the entire Squid proxy service, disrupting all web traffic that depends on the caching infrastructure. The attack requires no authentication or special privileges, making it an attractive target for malicious actors seeking to disrupt web services.
The operational impact of CVE-2023-49285 extends beyond simple service disruption to potentially compromise the availability of entire web infrastructures that depend on Squid caching proxies. Organizations using affected versions of Squid may experience complete service outages when attackers exploit this vulnerability, as the overread condition typically results in application crashes or memory corruption that requires manual intervention to resolve. The vulnerability's presence in HTTP message processing means that any web traffic passing through the affected proxy can potentially trigger the flaw, making it particularly dangerous in high-traffic environments where the attack surface is maximized. This type of vulnerability aligns with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries leverage software flaws to exhaust system resources or cause application failures. The lack of known workarounds means that organizations cannot temporarily mitigate the issue through configuration changes or patches, forcing them to rely entirely on upgrading to the patched version.
Organizations must prioritize immediate remediation of CVE-2023-49285 by upgrading to Squid version 6.5 or later, which contains the necessary fixes to prevent the buffer overread condition. The upgrade process should be carefully planned to minimize service disruption while ensuring all affected systems receive the security patch. Security teams should conduct thorough testing of the updated Squid version in staging environments before deploying to production systems to verify compatibility with existing configurations and caching policies. Additionally, monitoring should be implemented to detect any attempts to exploit this vulnerability through anomalous HTTP traffic patterns or repeated connection failures that may indicate active exploitation attempts. Network segmentation strategies should be considered to limit the potential impact of successful exploitation attempts, while also implementing intrusion detection systems that can identify malicious HTTP traffic patterns associated with this specific vulnerability. The vulnerability's classification as a denial of service issue underscores the importance of maintaining robust backup and failover mechanisms for critical web infrastructure components that rely on Squid proxy services.