CVE-2016-2569

HIGH

Squid 3.x < 3.5.15 and 4.x < 4.0.7 - Denial of Service via HTTP Vary Header

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2016-2569. PoCs published by amit-raut.

AI-analyzed exploit summary This repository provides a detailed technical analysis of CVE-2016-2569, a denial-of-service vulnerability in Squid proxy due to improper handling of long strings in String objects. It includes patch analysis, exploitation setup, and a Python script to test the vulnerability.

Description

Squid 3.x before 3.5.15 and 4.x before 4.0.7 does not properly append data to String objects, which allows remote servers to cause a denial of service (assertion failure and daemon exit) via a long string, as demonstrated by a crafted HTTP Vary header.

Exploits (2)

nomisec WRITEUP 6 stars
by amit-raut · poc
https://github.com/amit-raut/CVE-2016-2569

This repository provides a detailed technical analysis of CVE-2016-2569, a denial-of-service vulnerability in Squid proxy due to improper handling of long strings in String objects. It includes patch analysis, exploitation setup, and a Python script to test the vulnerability.

Classification
Writeup 95%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: Squid 3.x before 3.5.15 and 4.x before 4.0.7
No auth needed
Prerequisites: Squid proxy server with vulnerable version · Ability to send crafted HTTP requests
devstral-2 · analyzed Feb 18, 2026 Full analysis →
gitlab WRITEUP
by amit-raut · poc
https://gitlab.com/amit-raut/CVE-2016-2569

This repository provides a detailed technical analysis of CVE-2016-2569, a denial-of-service vulnerability in Squid Caching Proxy. It includes patch analysis, vulnerability root cause, and a step-by-step exploitation guide using a crafted HTTP Vary header.

Classification
Writeup 95%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: Squid Caching Proxy 3.x before 3.5.15 and 4.x before 4.0.7
No auth needed
Prerequisites: Squid Caching Proxy server · Python with requests library · Metanet or similar HTTP server for testing
devstral-2 · analyzed Feb 23, 2026 Full analysis →

References (11)

Core 11
Core References
Vendor Advisory vendor-advisory x_refsource_ubuntu
https://usn.ubuntu.com/3557-1/
Third Party Advisory vendor-advisory x_refsource_gentoo
https://security.gentoo.org/glsa/201607-01
Vendor Advisory x_refsource_confirm
http://www.squid-cache.org/Advisories/SQUID-2016_2.txt
Vendor Advisory vendor-advisory x_refsource_redhat
http://rhn.redhat.com/errata/RHSA-2016-2600.html
Mailing List vendor-advisory x_refsource_suse
http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
Mailing List mailing-list x_refsource_mlist
http://www.openwall.com/lists/oss-security/2016/02/26/2
Third Party Advisory, VDB Entry vdb-entry x_refsource_sectrack
http://www.securitytracker.com/id/1035101

Scores

CVSS v3 7.5
EPSS 0.7032
EPSS Percentile 98.7%
Attack Vector NETWORK
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Details

CWE
CWE-20
Status published
Products (40)
squid-cache/squid 3.0 (9 CPE variants)
squid-cache/squid 3.0.stable1
squid-cache/squid 3.0.stable2
squid-cache/squid 3.0.stable3
squid-cache/squid 3.0.stable4
squid-cache/squid 3.0.stable5
squid-cache/squid 3.0.stable6
squid-cache/squid 3.0.stable7
squid-cache/squid 3.0.stable8
squid-cache/squid 3.0.stable9
... and 30 more
Published Feb 27, 2016
Tracked Since Feb 18, 2026