# CVE-2023-23934: Incorrect parsing of nameless cookies leads to __Host- cookies bypass

Source: https://junglewise.ai/threats/cve-2023-23934-incorrect-parsing-of-nameless-cookies-leads-to-host-cookies  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2023-02-14  
License: CC BY 4.0 with a link back

CVE-2023-23934 · Severity: low · CVSS 3.1 · Published 2023-02-14

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.

Technologies: [werkzeug (PyPI)](https://junglewise.ai/threats/technologies/werkzeug). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2023-23934 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2023-23934 being exploited in the wild.

**How severe is CVE-2023-23934?** Low severity, with a CVSS score of 3.1, published 14 February 2023.

**Which products and versions are affected?** werkzeug (PyPI) ECOSYSTEM:introduced=0,fixed=2.2.3, GIT:introduced=0,fixed=cf275f42acad1b5950c50ffe8ef58fe62cdce028|ECOSYSTEM:introduced=0,fixed=2.2.3.

**Is there a fix for CVE-2023-23934?** Yes. werkzeug (PyPI): upgrade to 2.2.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2023-23934?** Check whether you run werkzeug (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- werkzeug (PyPI): upgrade to 2.2.3 or later

  ```sh
  pip install "werkzeug>=2.2.3"
  ```


## Affected products

- werkzeug (PyPI) ECOSYSTEM:introduced=0,fixed=2.2.3, GIT:introduced=0,fixed=cf275f42acad1b5950c50ffe8ef58fe62cdce028|ECOSYSTEM:introduced=0,fixed=2.2.3

## Identifiers

- CVE-2023-23934
- GHSA-px8h-6qxv-m22q
- PYSEC-2023-57

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- [PYSEC-2026-2044 - Werkzeug safe_join() allows Windows special device names with compound extensions](https://junglewise.ai/threats/cve-2026-21860-werkzeug-safe-join-allows-windows-special-device-names-with)
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- [PYSEC-2026-1065 - Pallets Werkzeug vulnerable to Path Traversal](https://junglewise.ai/threats/cve-2019-14322-pallets-werkzeug-vulnerable-to-path-traversal)