This indicates an attempt to exploit a Denial of Service vulnerability in Squid proxy.
The vulnerability is due to Edge Slides Includes (ESI) handling ESI response packets improperly. A remote attacker may be able to exploit this to cause a denial of service condition on the target via a crafted packet.
Squid Project Squid 3.x prior to 3.5.18
Squid Project Squid 4.x prior to 4.0.10
Denial of Service: Remote attackers can crash vulnerable systems.
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