CVE-2023-23934

Wrkzeug's incorrect parsing of nameless cookies leads to __Host- cookies bypass

Published Feb 14, 2023 CVSS 3.1 · 2.6 Low EPSS < 1% KEV · Not listed
Description
Werkzeug is a comprehensive WSGI web application library. Browsers may allow "nameless" cookies that look like `=value` instead of `key=value`. A vulnerable browser may allow a compromised application on an adjacent subdomain to exploit this to set a cookie like `=__Host-test=bad` for another subdomain. Werkzeug prior to 2.2.3 will parse the cookie `=__Host-test=bad` as __Host-test=bad`. If a Werkzeug application is running next to a vulnerable or malicious subdomain which sets such a cookie using a vulnerable browser, the Werkzeug application will see the bad cookie value but the valid cookie key. The issue is fixed in Werkzeug 2.2.3.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-3346-1 python-werkzeug security update
Debian DSA Debian DSA DSA-5470-1 python-werkzeug security update
EUVD EUVD EUVD-2023-0281 Werkzeug is a comprehensive WSGI web application library. Browsers may allow "nameless" cookies that look like `=value` instead of `key=value`. A vulnerable browser may allow a compromised application on an adjacent subdomain to exploit this to set a cookie like `=__Host-test=bad` for another subdomain. Werkzeug prior to 2.2.3 will parse the cookie `=__Host-test=bad` as __Host-test=bad`. If a Werkzeug application is running next to a vulnerable or malicious subdomain which sets such a cookie using a vulnerable browser, the Werkzeug application will see the bad cookie value but the valid cookie key. The issue is fixed in Werkzeug 2.2.3.
Github GHSA Github GHSA GHSA-px8h-6qxv-m22q Incorrect parsing of nameless cookies leads to __Host- cookies bypass
Ubuntu USN Ubuntu USN USN-5948-1 Werkzeug vulnerabilities
Ubuntu USN Ubuntu USN USN-5948-2 Werkzeug vulnerabilities
History
Type Values Removed Values Added
CPEs cpe:/a:redhat:ceph_storage:8.1::el9
Type Values Removed Values Added
First Time appeared Redhat ceph Storage
CPEs cpe:/a:redhat:ceph_storage:7.1::el8
Vendors & Products Redhat ceph Storage
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Mar 10, 2025, 9:11 PM
Reserved
Jan 19, 2023, 9:12 PM
Status
Modified
Published
Feb 14, 2023, 8:15 PM
Modified
Jun 17, 2026, 5:38 AM
Severity
Low
Public date
Feb 14, 2023, 12:00 AM