Squid Proxy ESI Component Buffer Overflow (May 6,2016)


Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. It reduces bandwidth and improves response times by caching and reusing frequently-requested web page.

Buffer overflow in Squid allows remote attackers to execute arbitrary code via crafted Edge Side Includes (ESI) responses.(CVE-2016-4054)

ESI is a small markup language for edge level dynamic web content assembly.A stack-based buffer overflow vulnerability exists in the Squid server. The vulnerability is due to an implementation error when the Squid server processes the ESI markup tags.

The vulnerable function is ESIContext::start() . Patch fixes the overflow by checking the size of buffer before copying.

Dell SonicWALL Threat Research Team has researched this vulnerability and released following signature to protect their customers

  • IPS 4902:Server Application Shellcode Exploit 20
    • Security News
      The SonicWall Capture Labs Threat Research Team gathers, analyzes and vets cross-vector threat information from the SonicWall Capture Threat network, consisting of global devices and resources, including more than 1 million security sensors in nearly 200 countries and territories. The research team identifies, analyzes, and mitigates critical vulnerabilities and malware daily through in-depth research, which drives protection for all SonicWall customers. In addition to safeguarding networks globally, the research team supports the larger threat intelligence community by releasing weekly deep technical analyses of the most critical threats to small businesses, providing critical knowledge that defenders need to protect their networks.