CVE-2023-23934
Wrkzeug's incorrect parsing of nameless cookies leads to __Host- cookies bypass
LOW 3.5EPSS 0.5%
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.
- Affected
- pallets · werkzeug
- CVSS v3.1 NVD
- 3.5 LOW
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N - CVSS v3.1 GITHUB
- 2.6 LOW
CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N - EPSS
- 0.51% chance of exploitation in the next 30 days, 42nd percentile
- Published
- 2023-02-14
- Updated
- 2025-03-10
Proof-of-concept exploits (1)
- SenhorDosSonhos1/projeto-voluntario-lacrei2★ · 2023-11-07
Security advisories
- pallets/werkzeug/security/advisories/GHSA-px8h-6qxv-m22q
- advisories/GHSA-px8h-6qxv-m22q
- pallets/werkzeug/commit/cf275f42acad1b5950c50ffe8ef58fe62cdce028