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Fencer Intel
high 7.5

CVE-2018-1000027 in the critical feed json

The Squid Software Foundation Squid HTTP Caching Proxy version prior to version 4.0.23 contains a NULL Pointer Dereference vulnerability in…

published 8y ago modified 4mo ago also EUVD-2018-1788

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
12.9%
EPSS 12.9% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

The Squid Software Foundation Squid HTTP Caching Proxy version prior to version 4.0.23 contains a NULL Pointer Dereference vulnerability in HTTP Response X-Forwarded-For header processing that can result in Denial of Service to all clients of the proxy. This attack appear to be exploitable via Remote HTTP server responding with an X-Forwarded-For header to certain types of HTTP request. This vulnerability appears to have been fixed in 4.0.23 and later.

Patch / fix

  • squid-cache squid 4.0.23
  • squid Debian 14, Debian 13, Debian 12 4.1-1

debian advisories DEBIAN-CVE-2018-1000027

  • squid3 Ubuntu 14.04 LTS 3.3.8-1ubuntu6.11
  • squid3 Ubuntu 16.04 LTS 3.5.12-1ubuntu7.5
  • squid3 Ubuntu 18.04 LTS 3.5.23-5ubuntu2

ubuntu advisories UBUNTU-CVE-2018-1000027

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • squid RHEL 7 7:3.5.20-15.el7
  • squid-sysvinit RHEL 7 7:3.5.20-15.el7
  • squid-migration-script RHEL 7 7:3.5.20-15.el7

red hat advisories RHSA-2020:1068

  • squid3 SLES for SAP 11 SP4, SLES 11 SP4 3.1.23-8.16.37.3.1
  • squid SLES for SAP 12 SP3, SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2 +2 more 3.5.21-26.6.1

suse advisories SUSE-SU-2018:0752-1SUSE-SU-2018:0636-1

  • squid openSUSE Tumbleweed 4.16-1.5

opensuse advisories openSUSE-SU-2024:11403-1

  • squid Alpine 3.24, Alpine 3.23, Alpine 3.22 +14 more 3.5.27-r2
  • squid Alpine 3.7, Alpine 3.6, Alpine 3.5 +1 more 3.5.27-r0

alpine advisories ALPINE-CVE-2018-1000027

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2018-1000027 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-1000027 updated cvss 6.8

squid: Incorrect pointer handling in HTTP processing and certificate download can lead to denial of service

  • Red Hat Enterprise Linux 6 squid, squid34
    affected: workaround, no fix planned “A workaround for this issue is to set the "log_uses_indirect_client off" configuration directive in the squid configuration file (for example /etc/squid/squid.conf).”
  • Red Hat Enterprise Linux Server (v. 7) squid 3.5.20-15.el7, squid-migration-script 3.5.20-15.el7 Red Hat Enterprise Linux Server Optional (v. 7) squid-sysvinit 3.5.20-15.el7 Red Hat Enterprise Linux Workstation (v. 7) squid 3.5.20-15.el7, squid-migration-script 3.5.20-15.el7 Red Hat Enterprise Linux Workstation Optional (v. 7) squid-sysvinit 3.5.20-15.el7
    fixed: vendor fix “A workaround for this issue is to set the "log_uses_indirect_client off" configuration directive in the squid configuration file (for example /etc/squid/squid.conf).” RHSA-2020:1068
  • Red Hat Enterprise Linux 5 squid Red Hat Enterprise Linux 8 squid, libecap
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

12.91% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.