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    CVE-2016-4553

    client_side.cc in Squid before 3.5.18 and 4.x before 4.0.10 does not properly ignore the Host header when absolute-URI is provided, which allows remote attackers to conduct cache-poisoning attacks via an HTTP request.

    Published:May 6, 2016
    Last Modified:Apr 12, 2025
    EPS:May 10, 2016
    EPSS Score:0.39528
    CVSS Score:8.6

    Affected Products

    Vendor
    Canonical
    Product
    Ubuntu Linux
    Vendor
    Oracle
    Product
    Linux
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    Squid-cache
    Product
    Squid

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-10 Buffer Overflow via Environment Variables
    CAPEC-101 Server Side Include (SSI) Injection
    CAPEC-104 Cross Zone Scripting
    CAPEC-108 Command Line Execution through SQL Injection
    CAPEC-109 Object Relational Mapping Injection
    CAPEC-110 SQL Injection through SOAP Parameter Tampering
    CAPEC-111 JSON Hijacking (aka JavaScript Hijacking)
    CAPEC-120 Double Encoding
    CAPEC-13 Subverting Environment Variable Values
    CAPEC-135 Format String Injection
    CAPEC-136 LDAP Injection
    CAPEC-14 Client-side Injection-induced Buffer Overflow
    CAPEC-141 Cache Poisoning
    CAPEC-142 DNS Cache Poisoning
    CAPEC-148 Content Spoofing
    CAPEC-153 Input Data Manipulation
    CAPEC-182 Flash Injection
    CAPEC-209 XSS Using MIME Type Mismatch
    CAPEC-218 Spoofing of UDDI/ebXML Messages
    CAPEC-22 Exploiting Trust in Client
    CAPEC-23 File Content Injection
    CAPEC-230 Serialized Data with Nested Payloads
    CAPEC-231 Oversized Serialized Data Payloads
    CAPEC-24 Filter Failure through Buffer Overflow
    CAPEC-250 XML Injection
    CAPEC-261 Fuzzing for garnering other adjacent user/sensitive data
    CAPEC-267 Leverage Alternate Encoding
    CAPEC-28 Fuzzing
    CAPEC-3 Using Leading 'Ghost' Character Sequences to Bypass Input Filters
    CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies
    CAPEC-384 Application API Message Manipulation via Man-in-the-Middle
    CAPEC-385 Transaction or Event Tampering via Application API Manipulation
    CAPEC-386 Application API Navigation Remapping
    CAPEC-387 Navigation Remapping To Propagate Malicious Content
    CAPEC-388 Application API Button Hijacking
    CAPEC-42 MIME Conversion
    CAPEC-43 Exploiting Multiple Input Interpretation Layers
    CAPEC-45 Buffer Overflow via Symbolic Links
    CAPEC-46 Overflow Variables and Tags
    CAPEC-47 Buffer Overflow via Parameter Expansion
    CAPEC-473 Signature Spoof
    CAPEC-52 Embedding NULL Bytes
    CAPEC-53 Postfix, Null Terminate, and Backslash
    CAPEC-588 DOM-Based XSS
    CAPEC-63 Cross-Site Scripting (XSS)
    CAPEC-64 Using Slashes and URL Encoding Combined to Bypass Validation Logic
    CAPEC-664 Server Side Request Forgery
    CAPEC-665 Exploitation of Thunderbolt Protection Flaws
    CAPEC-67 String Format Overflow in syslog()
    CAPEC-7 Blind SQL Injection
    CAPEC-701 Browser in the Middle (BiTM)
    CAPEC-71 Using Unicode Encoding to Bypass Validation Logic
    CAPEC-72 URL Encoding
    CAPEC-73 User-Controlled Filename
    CAPEC-78 Using Escaped Slashes in Alternate Encoding
    CAPEC-79 Using Slashes in Alternate Encoding
    CAPEC-8 Buffer Overflow in an API Call
    CAPEC-80 Using UTF-8 Encoding to Bypass Validation Logic
    CAPEC-81 Web Server Logs Tampering
    CAPEC-83 XPath Injection
    CAPEC-85 AJAX Footprinting
    CAPEC-88 OS Command Injection
    CAPEC-9 Buffer Overflow in Local Command-Line Utilities

    Related CVEs

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    CVE-2026-47336 (CVSS 3.3) — Ubuntu Linux 6.8 contains SAUCE patches with a possible use of an uninitialized variable in AppArmor AF_INET/A…
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    CVE-2026-47334 (CVSS 5.5) — Ubuntu Linux 6.8, 6.17 and 7.0 contain AppArmor SAUCE patches which incorrectly sleep while holding a spinlock…
    CVE-2026-47333 (CVSS 7.8) — Ubuntu Linux 6.8, 6.17 and 7.0 contain AppArmor SAUCE patches which can potentially incorrectly compute the si…
    CVE-2026-47332 (CVSS 5.5) — Ubuntu Linux 6.8, 6.17 and 7.0 contain AppArmor SAUCE patches which incorrectly validate the size of an intern…
    CVE-2026-47331 (CVSS 7.8) — Ubuntu Linux 6.8 contains AppArmor SAUCE patches which fail to acquire a lock when modifying a linked list. An…
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    References

    http://bugs.squid-cache.org/show_bug.cgi?id=4501
    http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
    http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
    http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
    http://www.debian.org/security/2016/dsa-3625
    http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
    http://www.securitytracker.com/id/1035768
    http://www.squid-cache.org/Advisories/SQUID-2016_7.txt
    http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14039.patch
    http://www.ubuntu.com/usn/USN-2995-1
    https://access.redhat.com/errata/RHSA-2016:1139
    https://access.redhat.com/errata/RHSA-2016:1140
    https://security.gentoo.org/glsa/201607-01
    http://bugs.squid-cache.org/show_bug.cgi?id=4501
    http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
    http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
    http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
    http://www.debian.org/security/2016/dsa-3625
    http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
    http://www.securitytracker.com/id/1035768
    http://www.squid-cache.org/Advisories/SQUID-2016_7.txt
    http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14039.patch
    http://www.ubuntu.com/usn/USN-2995-1
    https://access.redhat.com/errata/RHSA-2016:1139
    https://access.redhat.com/errata/RHSA-2016:1140
    https://security.gentoo.org/glsa/201607-01

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High