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Full vulnerability report · 2019
CVE-2018-20852High confidence

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)

Unknown · Unknown

4.3MediumCVSS 3.1
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 5 Aug 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 3.67% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

2 current
CVE-2018-20852 · CSAF 2.0 · revision 48 · interimSUSE Product Security TeamCVE-2018-20852
160 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • python as component of HPE Helion OpenStack 8
  • python-32bit as component of HPE Helion OpenStack 8
  • python-curses as component of HPE Helion OpenStack 8
  • python-demo as component of HPE Helion OpenStack 8
  • python-gdbm as component of HPE Helion OpenStack 8
  • python-idle as component of HPE Helion OpenStack 8
  • python-tk as component of HPE Helion OpenStack 8
  • python3 as component of HPE Helion OpenStack 8
  • python3-curses as component of HPE Helion OpenStack 8
  • python as component of SUSE CaaS Platform 4.0
  • python-curses as component of SUSE CaaS Platform 4.0
  • python-gdbm as component of SUSE CaaS Platform 4.0
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.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
CVE-2018-20852 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitypython: Cookie domain check returns incorrect results
8 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • python.src as a component of Red Hat Enterprise Linux 5
  • python as a component of Red Hat Enterprise Linux 6
  • python-devel as a component of Red Hat Enterprise Linux 6
  • python-libs as a component of Red Hat Enterprise Linux 6
  • python-test as a component of Red Hat Enterprise Linux 6
  • python-tools as a component of Red Hat Enterprise Linux 6
  • python.src as a component of Red Hat Enterprise Linux 6
  • tkinter as a component of Red Hat Enterprise Linux 6
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.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2018-13392

No EUVD known-exploited evidence

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.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
4.3 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

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.

What

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.

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

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.

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Input Validation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-20 ↗

CWE-20: Improper Input Validation. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-20Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2018-13392Official EUVD mapping

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.

Official EUVD record ↗
BSI · German · WID-SEC-2026-4026Red Hat OpenShift: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Red Hat OpenShift ausnutzen, um die Vertraulichkeit, Verfügbarkeit und Integrität zu gefährden.

Official advisory ↗
BSI · German · WID-SEC-2024-1597Python: Schwachstelle ermöglicht Offenlegung von Informationen

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Python ausnutzen, um Informationen offenzulegen.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0395Multiples vulnérabilités dans les produits IBM

www.ibm.com/support/pages/node/7267689 Bulletin de sécurité IBM 7267801 du 27 mars 2026 https://www.ibm.com/support/pages/node/7267801 Bulletin de sécurité IBM 7268179 du 31 mars 2026 https://www.ibm.com/support/pages/node/7268179 Bulletin de sécurité IBM 7268331 du 01 avril 2026 https://www.ibm.com/support/pages/node/7268331 Référence CVE CVE-2015-20107 https://www.cve.org/CVERecord?id=CVE-2015-20107 Référence CVE CVE-2017-18342 https://www.cve.org/CVERecord?id=CVE-2017-18342 Référence CVE CVE-2018-18074 https://www.cve.org/CVERecord?id=CVE-2018-18074 Référence CVE CVE-2018-20060 https://www.cve.org/CVERecord?id=CVE-2018-20060 Référence CVE CVE-2018-20852 https://www.cve.org/CVERecord?id=CVE-2018-20852 Référence CVE CVE-2019-11236 https://www.cve.org/CVERecord?id=CVE-2019-11236 Référence CVE CVE-2019-11324 https://www.cve.org/CVERecord?id=CVE-2019-11324 Référence CVE CVE-2019-11340 https://www.cve.org/CVERecord?id=CVE-2019-11340 Référence CVE CVE-2019-16056 https://www.cve.org/CVERecord?id=CVE-2019-16056 Référence CVE CVE-2019-16935 https://www.cve.org/CVERecord?id=CVE-2019-16935 Référence CVE CVE-2019-18874 https://www.cve.org/CVERecord?id=CVE-2019-18874 Référence CVE CVE-2019-20477 https://www.cve.org/CVERecord?id=CVE-2019-20477 Référence CVE CVE-2019-20907 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-928Multiples vulnérabilités dans les produits IBM

rité IBM 6830257 du 18 octobre 2022 https://www.ibm.com/support/pages/node/6830257 Bulletin de sécurité IBM 6830265 du 18 octobre 2022 https://www.ibm.com/support/pages/node/6830265 Référence CVE CVE-2011-4969 https://www.cve.org/CVERecord?id=CVE-2011-4969 Référence CVE CVE-2012-5783 https://www.cve.org/CVERecord?id=CVE-2012-5783 Référence CVE CVE-2012-6708 https://www.cve.org/CVERecord?id=CVE-2012-6708 Référence CVE CVE-2015-9251 https://www.cve.org/CVERecord?id=CVE-2015-9251 Référence CVE CVE-2018-16487 https://www.cve.org/CVERecord?id=CVE-2018-16487 Référence CVE CVE-2018-20406 https://www.cve.org/CVERecord?id=CVE-2018-20406 Référence CVE CVE-2018-20852 https://www.cve.org/CVERecord?id=CVE-2018-20852 Référence CVE CVE-2018-25031 https://www.cve.org/CVERecord?id=CVE-2018-25031 Référence CVE CVE-2018-3721 https://www.cve.org/CVERecord?id=CVE-2018-3721 Référence CVE CVE-2019-0205 https://www.cve.org/CVERecord?id=CVE-2019-0205 Référence CVE CVE-2019-1010266 https://www.cve.org/CVERecord?id=CVE-2019-1010266 Référence CVE CVE-2019-10172 https://www.cve.org/CVERecord?id=CVE-2019-10172 Référence CVE CVE-2019-10202 https://www.cve.org/CVERecord?id=CVE-2019-10202 Référence CVE CVE-2019-10744 https://www.cve.org/CVERecord?id=CVE-2019-10744 Référence CVE CVE-2019-11358 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-267Multiples vulnérabilités dans Juniper Networks Junos Space

d?id=CVE-2018-18521 Référence CVE CVE-2018-18751 https://www.cve.org/CVERecord?id=CVE-2018-18751 Référence CVE CVE-2018-19519 https://www.cve.org/CVERecord?id=CVE-2018-19519 Référence CVE CVE-2018-19788 https://www.cve.org/CVERecord?id=CVE-2018-19788 Référence CVE CVE-2018-19985 https://www.cve.org/CVERecord?id=CVE-2018-19985 Référence CVE CVE-2018-20060 https://www.cve.org/CVERecord?id=CVE-2018-20060 Référence CVE CVE-2018-20169 https://www.cve.org/CVERecord?id=CVE-2018-20169 Référence CVE CVE-2018-20836 https://www.cve.org/CVERecord?id=CVE-2018-20836 Référence CVE CVE-2018-20843 https://www.cve.org/CVERecord?id=CVE-2018-20843 Référence CVE CVE-2018-20852 https://www.cve.org/CVERecord?id=CVE-2018-20852 Référence CVE CVE-2018-3639 https://www.cve.org/CVERecord?id=CVE-2018-3639 Référence CVE CVE-2018-4180 https://www.cve.org/CVERecord?id=CVE-2018-4180 Référence CVE CVE-2018-4181 https://www.cve.org/CVERecord?id=CVE-2018-4181 Référence CVE CVE-2018-4700 https://www.cve.org/CVERecord?id=CVE-2018-4700 Référence CVE CVE-2018-5407 https://www.cve.org/CVERecord?id=CVE-2018-5407 Référence CVE CVE-2018-5683 https://www.cve.org/CVERecord?id=CVE-2018-5683 Référence CVE CVE-2018-5729 https://www.cve.org/CVERecord?id=CVE-2018-5729 Référence CVE CVE-2018-5730 https://www.cve.org/CVERecord?id=CVE-2018-5730 R

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2018-015872Python における入力確認に関する脆弱性

Python には、入力確認に関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Action
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 13 Jul 2019 · Last source change 7 Oct 2026, 18:24 UTC · CWE-20 · Improper Input Validation

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-01
European sourceENISA EUVD · EUVD-2018-13392
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceCISA ADP
NVD statusNVD modified after enrichment

Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    n/a · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
    Red Hat Product Security ↗
  2. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
  3. CVSS scoreCVSS score changed from 5.3 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) to 4.3 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N).
    Before
    5.3 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
    After
    4.3 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N)
    CISA ADP ↗
  4. ENISA EUVD mappingEUVD-2018-13392 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2018-13392"}
    ENISA EUVD ↗
  5. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: bugs.python.org/issue35121; added vendor advisory: python-security.readthedocs.io/cookie-domain-check.html; removed vendor advisory: access.redhat.com/RHSA-2019:3725; removed vendor advisory: access.redhat.com/RHSA-2019:3948; 9 further removals.
    Before
    vendor advisory: access.redhat.com/RHSA-2019:3725 · vendor advisory: access.redhat.com/RHSA-2019:3948 · vendor advisory: lists.fedoraproject.org/COATURTCY7G67AYI6UDV5B2JZTBCKIDX · 8 more references
    After
    vendor advisory: bugs.python.org/issue35121 · vendor advisory: python-security.readthedocs.io/cookie-domain-check.html
    bugs.python.org ↗
  6. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    bugs.python.org ↗
  7. SeveritySeverity changed from Unknown to Medium.
    Before
    Unknown
    After
    Medium
    NIST NVD ↗
  8. CVSS scoreCVSS score changed from not recorded to 5.3 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).
    Before
    not recorded
    After
    5.3 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
    NIST NVD ↗
  9. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2018-13392↗Vendor CSAF · SUSE Product Security Team↗Red Hat Product Security security advisory↗Public exploit reference↗Vendor advisory↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2018-20852 · cve.blacktree.nl