{"cve":"CVE-2023-23934","nvd":{"published":"2023-02-14T20:15:17.370","modified":"2026-06-17T05:38:19.313","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N","score":3.5},"cwes":["CWE-20"],"references":["https://github.com/pallets/werkzeug/commit/cf275f42acad1b5950c50ffe8ef58fe62cdce028","https://github.com/pallets/werkzeug/releases/tag/2.2.3","https://github.com/pallets/werkzeug/security/advisories/GHSA-px8h-6qxv-m22q","https://security.netapp.com/advisory/ntap-20230818-0003/","https://www.debian.org/security/2023/dsa-5470"],"products":["palletsprojects:werkzeug"],"source":"nvd","synced_at":"2026-10-19T21:37:38.595364862+00:00"},"epss":{"cve":"CVE-2023-23934","score":0.00507,"percentile":0.43282,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-px8h-6qxv-m22q","url":"https://osv.dev/vulnerability/GHSA-px8h-6qxv-m22q","summary":"Incorrect parsing of nameless cookies leads to __Host- cookies bypass","modified":"2026-09-10T03:50:07.890803222Z","packages":[{"ecosystem":"PyPI","name":"werkzeug","purl":"pkg:pypi/werkzeug","ranges":["<2.2.3"],"fixed":["2.2.3"]}]},{"id":"PYSEC-2023-57","url":"https://osv.dev/vulnerability/PYSEC-2023-57","summary":"","modified":"2023-11-08T04:11:43.091670Z","packages":[{"ecosystem":"PyPI","name":"werkzeug","purl":"pkg:pypi/werkzeug","ranges":["<2.2.3"],"fixed":["2.2.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}