{"id":"CVE-2023-23934","aliases":["GHSA-px8h-6qxv-m22q","PYSEC-2023-57"],"url":"https://o3.security/vulnerability/CVE-2023-23934","summary":"Wrkzeug's incorrect parsing of nameless cookies leads to __Host- cookies bypass","details":"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.","published":"2023-02-14T19:56:22.659Z","modified":"2026-08-12T03:51:19.151575995Z","cvss":{"score":2.6,"severity":"LOW","vector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"werkzeug","fixedVersion":"2.2.3"}],"fix":{"url":"https://github.com/pallets/werkzeug/commit/cf275f42acad1b5950c50ffe8ef58fe62cdce028","label":"pallets/werkzeug@cf275f4"},"references":[{"type":"WEB","url":"https://github.com/pallets/werkzeug/releases/tag/2.2.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/23xxx/CVE-2023-23934.json"},{"type":"ADVISORY","url":"https://github.com/pallets/werkzeug/security/advisories/GHSA-px8h-6qxv-m22q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-23934"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20230818-0003/"},{"type":"ADVISORY","url":"https://www.debian.org/security/2023/dsa-5470"},{"type":"FIX","url":"https://github.com/pallets/werkzeug/commit/cf275f42acad1b5950c50ffe8ef58fe62cdce028"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:19.151575995Z"}}