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CVE-2016-2569

Squid 3.x before 3.5.15 and 4.x before 4.0.7 does not properly append data to String objects,...

7.5 HighPublic exploitFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

31.2%Up 14.9 points since Feb 4, 2022
90%50%10%1%

What each source reports

NVD Score used 7.5

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.

Record
CVE-2016-2569
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-20
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2016-2569
Updated
2026-11-02
EUVDEUVD-2016-3643 No score

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.

Record
EUVD-2016-3643
Updated
2026-11-03
GitHub AdvisoriesGHSA-6gm6-3v5f-xfhg 7.5

Squid 3.x before 3.5.15 and 4.x before 4.0.7 does not properly append data to String objects,...

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.

Record
GHSA-6gm6-3v5f-xfhg
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-20
Updated
2026-11-02
OSV 7.5

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.

Record
CVE-2016-2569
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2016-2569 7.5

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.

Record
UBUNTU-CVE-2016-2569
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 5 moreShow less
OSVMGASA-2016-0095 No score

Updated squid packages fix security vulnerabilities

Updated squid packages fix security vulnerability:

Due to incorrect bounds checking Squid is vulnerable to a denial of service attack when processing HTTP responses (CVE-2016-2569, CVE-2016-2570, CVE-2016-2571).

Record
MGASA-2016-0095
Updated
2026-11-02
OSVopenSUSE-SU-2024:11403-1 No score

squid-4.16-1.5 on GA media

These are all security issues fixed in the squid-4.16-1.5 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:11403-1
Updated
2026-11-02
OSVSUSE-SU-2016:2008-1 No score

Security update for squid

The Squid HTTP proxy has been updated to version 3.3.14, fixing the following security issues:

  • Fixed multiple Denial of Service issues in HTTP Response processing. (CVE-2016-2569, CVE-2016-2570, CVE-2016-2571, CVE-2016-2572, bsc#968392, bsc#968393, bsc#968394, bsc#968395)
  • CVE-2016-3947: Buffer overrun issue in pinger ICMPv6 processing. (bsc#973782)
  • CVE-2015-5400: Improper protection of alternate path. (bsc#938715)
  • CVE-2015-3455: Squid http proxy configured with client-first SSL bumping did not correctly validate server certificate. (bsc#929493)
  • CVE-2016-3948: Fixed denial of service in HTTP Response processing (bsc#973783)
  • CVE-2016-4051: fixes buffer overflow in cachemgr.cgi (bsc#976553)
  • CVE-2016-4052, CVE-2016-4053, CVE-2016-4054: Fixed multiple issues in ESI processing (bsc#976556)
  • CVE-2016-4553: Fixed cache poisoning issue in HTTP Request handling (bsc#979009)
  • CVE-2016-4554: Fixed header smuggling issue in HTTP Request processing (bsc#979010)
  • Fixed multiple Denial of Service issues in ESI Response processing. (CVE-2016-4555, CVE-2016-4556, bsc#979011, bsc#979008)

Additionally, the following non-security issues have been fixed:

  • Fix header size in script unsquid.pl. (bsc#902197)
  • Add external helper ext_session_acl to package. (bsc#959290)
  • Update forward_max_tries to permit 25 server paths With cloud sites becoming more popular more CDN servers are producing long lists of IPv6 and IPv4 addresses. If there are not enough paths selected the IPv4 ones may never be reached.
  • squid.init: wait that squid really dies when we kill it on upgrade instead of proclaiming its demise prematurely (bnc#963539)
Record
SUSE-SU-2016:2008-1
Updated
2026-11-02
OSVSUSE-SU-2016:2089-1 No score

Security update for squid3

This update for squid3 fixes the following issues:

  • Multiple issues in pinger ICMP processing. (CVE-2014-7141, CVE-2014-7142)

  • CVE-2016-3947: Buffer overrun issue in pinger ICMPv6 processing. (bsc#973782)

  • CVE-2016-4554: fix header smuggling issue in HTTP Request processing (bsc#979010)

  • Fix multiple Denial of Service issues in HTTP Response processing. (CVE-2016-2569, CVE-2016-2570, CVE-2016-2571, CVE-2016-2572, bsc#968392, bsc#968393, bsc#968394, bsc#968395)

  • Regression caused by the DoS fixes above (bsc#993299)

  • CVE-2016-3948: Fix denial of service in HTTP Response processing (bsc#973783)

  • CVE-2016-4051: fixes buffer overflow in cachemgr.cgi (bsc#976553)

  • CVE-2016-4052, CVE-2016-4053, CVE-2016-4054:

    • fixes multiple issues in ESI processing (bsc#976556)

  • CVE-2016-4556: fixes double free vulnerability in Esi.cc (bsc#979008)

  • CVE-2015-5400: Improper Protection of Alternate Path (bsc#938715)

  • CVE-2014-6270: fix off-by-one in snmp subsystem (bsc#895773)

  • Memory leak in squid3 when using external_acl (bsc#976708)

Record
SUSE-SU-2016:2089-1
Updated
2026-11-02
OSVUSN-3557-1 No score

squid3 vulnerabilities

Mathias Fischer discovered that Squid incorrectly handled certain long strings in headers. A malicious remote server could possibly cause Squid to crash, resulting in a denial of service. This issue was only addressed in Ubuntu 16.04 LTS. (CVE-2016-2569)

William Lima discovered that Squid incorrectly handled XML parsing when processing Edge Side Includes (ESI). A malicious remote server could possibly cause Squid to crash, resulting in a denial of service. This issue was only addressed in Ubuntu 16.04 LTS. (CVE-2016-2570)

Alex Rousskov discovered that Squid incorrectly handled response-parsing failures. A malicious remote server could possibly cause Squid to crash, resulting in a denial of service. This issue only applied to Ubuntu 16.04 LTS. (CVE-2016-2571)

Santiago Ruano Rincón discovered that Squid incorrectly handled certain Vary headers. A remote attacker could possibly use this issue to cause Squid to crash, resulting in a denial of service. This issue was only addressed in Ubuntu 16.04 LTS. (CVE-2016-3948)

Louis Dion-Marcil discovered that Squid incorrectly handled certain Edge Side Includes (ESI) responses. A malicious remote server could possibly cause Squid to crash, resulting in a denial of service. (CVE-2018-1000024)

Louis Dion-Marcil discovered that Squid incorrectly handled certain Edge Side Includes (ESI) responses. A malicious remote server could possibly cause Squid to crash, resulting in a denial of service. (CVE-2018-1000027)

Record
USN-3557-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
squid
Mageia:5
 before 3.4.13-1.4.mga5
3.4.13-1.4.mga5
squid-debuginfo
Red Hat:enterprise_linux:7::server
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid-sysvinit
Red Hat:enterprise_linux:7::server
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid
Red Hat:enterprise_linux:7::server
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid-migration-script
Red Hat:enterprise_linux:7::server
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid-debuginfo
Red Hat:enterprise_linux:7::workstation
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid-sysvinit
Red Hat:enterprise_linux:7::workstation
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid
Red Hat:enterprise_linux:7::workstation
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid-migration-script
Red Hat:enterprise_linux:7::workstation
 before 7:3.5.20-2.el7
7:3.5.20-2.el7
squid
SUSE:Linux Enterprise Server 12 SP1
 before 3.3.14-20.2
3.3.14-20.2
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Affected packages
PackageAffectedFixed
squid
SUSE:Linux Enterprise Server for SAP Applications 12 SP1
 before 3.3.14-20.2
3.3.14-20.2
squid3
SUSE:Linux Enterprise Server 11 SP4
 before 3.1.23-8.16.30.1
3.1.23-8.16.30.1
squid3
SUSE:Linux Enterprise Server for SAP Applications 11 SP4
 before 3.1.23-8.16.30.1
3.1.23-8.16.30.1
squid3
Ubuntu:16.04:LTS
 before 3.5.12-1ubuntu7.5, plus listed versions
3.3.8-1ubuntu163.3.8-1ubuntu173.5.12-1ubuntu63.5.12-1ubuntu73.5.12-1ubuntu7.13.5.12-1ubuntu7.23.5.12-1ubuntu7.33.5.12-1ubuntu7.4
3.5.12-1ubuntu7.5
squid3
Ubuntu:14.04:LTS
 before 3.3.8-1ubuntu6.11, plus listed versions
3.3.8-1ubuntu33.3.8-1ubuntu43.3.8-1ubuntu53.3.8-1ubuntu63.3.8-1ubuntu6.1
Show 7 moreShow less
3.3.8-1ubuntu6.23.3.8-1ubuntu6.33.3.8-1ubuntu6.43.3.8-1ubuntu6.63.3.8-1ubuntu6.83.3.8-1ubuntu6.93.3.8-1ubuntu6.10
3.3.8-1ubuntu6.11
squid
openSUSE:Tumbleweed
 before 4.16-1.5
4.16-1.5

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
PoC in GitHubamit-raut/CVE-2016-25692018-02-03

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV, PoC in GitHub

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2016-2569 is a high vulnerability (CVSS 7.5) in Squid-cache Squid, published February 27, 2016. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 31.2%, the 98th percentile. Fixed in squid 3.4.13-1.4.mga5.

References

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