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CVE-2015-5400

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with...

6.8 MediumFix available

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Exploit likelihood

20.8%Up 17.1 points since Feb 4, 2022
90%50%10%1%

What each source reports

NVD Score used 6.8

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Record
CVE-2015-5400
CVSS 2.0
6.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness
CWE-264
Updated
2026-11-02
CVE List No score

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Record
CVE-2015-5400
Updated
2026-11-02
EUVDEUVD-2015-5356 No score

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Record
EUVD-2015-5356
Updated
2026-11-03
GitHub AdvisoriesGHSA-9pj4-fqm8-w5x7 No score

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with...

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Record
GHSA-9pj4-fqm8-w5x7
Updated
2026-11-02
OSV No score

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Record
CVE-2015-5400
Updated
2026-11-02
OSVDEBIAN-CVE-2015-5400 No score

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Record
DEBIAN-CVE-2015-5400
Updated
2026-11-02
Show 5 moreShow less
OSVMGASA-2015-0347 No score

Updated squid packages fix CVE-2015-5400

Updated squid packages fix security vulnerability:

Alex Rousskov discovered that Squid configured with cache_peer and operating on explicit proxy traffic does not correctly handle CONNECT method peer responses. In some configurations, it allows remote clients to bypass security in an explicit gateway proxy (CVE-2015-5400).

Record
MGASA-2015-0347
Updated
2026-11-02
OSVopenSUSE-SU-2024:10307-1 No score

squid-3.5.22-1.1 on GA media

These are all security issues fixed in the squid-3.5.22-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:10307-1
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
OSVUBUNTU-CVE-2015-5400 No score

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Record
UBUNTU-CVE-2015-5400
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
squid
Debian:12
before 4.1-1
4.1-1
squid
Debian:13
before 4.1-1
4.1-1
squid
Debian:14
before 4.1-1
4.1-1
squid3
Debian:6.0
before 3.1.6-1.2+squeeze5, plus listed versions
3.1.6-1.23.1.6-1.2+squeeze13.1.6-1.2+squeeze23.1.6-1.2+squeeze33.1.6-1.2+squeeze4
3.1.6-1.2+squeeze5
squid3
Debian:7
before 3.1.20-2.2+deb7u3, plus listed versions
3.1.20-2.23.1.20-2.2+deb7u13.1.20-2.2+deb7u2
3.1.20-2.2+deb7u3
squid3
Debian:8
before 3.4.8-6+deb8u1, plus listed versions
3.4.8-6
3.4.8-6+deb8u1
squid
Mageia:5
before 3.4.13-1.1.mga5
3.4.13-1.1.mga5
squid
SUSE:Linux Enterprise Server 12 SP1
From an advisory covering 16 CVEs
before 3.3.14-20.2
3.3.14-20.2
squid
SUSE:Linux Enterprise Server for SAP Applications 12 SP1
From an advisory covering 16 CVEs
before 3.3.14-20.2
3.3.14-20.2
squid3
SUSE:Linux Enterprise Server 11 SP4
From an advisory covering 25 CVEs
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
From an advisory covering 25 CVEs
before 3.1.23-8.16.30.1
3.1.23-8.16.30.1
squid3
Ubuntu:16.04:LTS
before 3.5.12-1ubuntu6, plus listed versions
3.3.8-1ubuntu163.3.8-1ubuntu17
3.5.12-1ubuntu6
squid
openSUSE:Tumbleweed
From an advisory covering 4 CVEs
before 3.5.22-1.1
3.5.22-1.1

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2015-5400 is a medium vulnerability (CVSS 6.8) in Squid-cache Squid, published July 30, 2015. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 20.8%, the 97th percentile. Fixed in squid 4.1-1.

References

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