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Vulnerability details: VCID-cpkh-xpsk-nqf1
Vulnerability ID VCID-cpkh-xpsk-nqf1
Aliases CVE-2018-20852
Summary http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong server. An attacker may abuse this flaw by using a server with a hostname that has another valid hostname as a suffix (e.g., pythonicexample.com to steal cookies for example.com). When a program uses http.cookiejar.DefaultPolicy and tries to do an HTTP connection to an attacker-controlled server, existing cookies can be leaked to the attacker. This affects 2.x through 2.7.16, 3.x before 3.4.10, 3.5.x before 3.5.7, 3.6.x before 3.6.9, and 3.7.x before 3.7.3.
Status Published
Exploitability 0.5
Weighted Severity 4.8
Risk 2.4
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-20 Improper Input Validation
System Score Found at
cvssv3 5.3 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2018-20852.json
epss 0.01665 https://api.first.org/data/v1/epss?cve=CVE-2018-20852
epss 0.01665 https://api.first.org/data/v1/epss?cve=CVE-2018-20852
epss 0.01665 https://api.first.org/data/v1/epss?cve=CVE-2018-20852
epss 0.01665 https://api.first.org/data/v1/epss?cve=CVE-2018-20852
cvssv3 5.3 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2018-20852.json
https://api.first.org/data/v1/epss?cve=CVE-2018-20852
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-20852
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
1740347 https://bugzilla.redhat.com/show_bug.cgi?id=1740347
GLSA-202003-26 https://security.gentoo.org/glsa/202003-26
RHSA-2019:3725 https://access.redhat.com/errata/RHSA-2019:3725
RHSA-2019:3948 https://access.redhat.com/errata/RHSA-2019:3948
RHSA-2020:1131 https://access.redhat.com/errata/RHSA-2020:1131
RHSA-2020:1132 https://access.redhat.com/errata/RHSA-2020:1132
RHSA-2020:1605 https://access.redhat.com/errata/RHSA-2020:1605
RHSA-2020:1764 https://access.redhat.com/errata/RHSA-2020:1764
USN-4127-1 https://usn.ubuntu.com/4127-1/
USN-4127-2 https://usn.ubuntu.com/4127-2/
USN-6891-1 https://usn.ubuntu.com/6891-1/
No exploits are available.
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2018-20852.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.82424
EPSS Score 0.01665
Published At June 4, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-04T17:08:36.033617+00:00 Debian Importer Import https://security-tracker.debian.org/tracker/data/json 38.6.0