{"cve":"CVE-2026-41059","nvd":{"published":"2026-04-22T00:16:27.957","modified":"2026-06-17T10:46:06.260","status":"Analyzed","description":"OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers. Versions 7.5.0 through 7.15.1 have a configuration-dependent authentication bypass. Deployments are affected when all of the following are true: Use of `skip_auth_routes` or the legacy `skip_auth_regex`; use of patterns that can be widened by attacker-controlled suffixes, such as `^/foo/.*/bar$` causing potential exposure of `/foo/secret`; and protected upstream applications that interpret `#` as a fragment delimiter or otherwise route the request to the protected base path. In deployments that rely on these settings, an unauthenticated attacker can send a crafted request containing a number sign in the path, including the browser-safe encoded form `%23`, so that OAuth2 Proxy matches a public allowlist rule while the backend serves a protected resource. Deployments that do not use these skip-auth options, or that only allow exact public paths with tightly scoped method and path rules, are not affected. A fix has been implemented in version 7.15.2 to normalize request paths more conservatively before skip-auth matching so fragment content does not influence allowlist decisions. Users who cannot upgrade immediately can reduce exposure by tightening or removing `skip_auth_routes` and `skip_auth_regex` rules, especially patterns that use broad wildcards across path segments. Recommended mitigations include replacing broad rules with exact, anchored public paths and explicit HTTP methods; rejecting requests whose path contains `%23` or `#` at the ingress, load balancer, or WAF level; and/or avoiding placing sensitive application paths behind broad `skip_auth_routes` rules.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","score":8.2},"cwes":["CWE-288"],"references":["https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-pxq7-h93f-9jrg"],"products":["oauth2_proxy_project:oauth2_proxy"],"source":"nvd","synced_at":"2026-10-19T22:30:49.762551342+00:00"},"epss":{"cve":"CVE-2026-41059","score":0.00275,"percentile":0.19924,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-pxq7-h93f-9jrg","url":"https://osv.dev/vulnerability/GHSA-pxq7-h93f-9jrg","summary":"OAuth2 Proxy has an Authentication Bypass via Fragment Confusion in skip_auth_routes and skip_auth_regex","modified":"2026-06-25T23:11:28.958923022Z","packages":[{"ecosystem":"Go","name":"github.com/oauth2-proxy/oauth2-proxy/v7","purl":"pkg:golang/github.com/oauth2-proxy/oauth2-proxy/v7","ranges":[">=7.5.0 <7.15.2"],"fixed":["7.15.2"]}]},{"id":"GO-2026-5559","url":"https://osv.dev/vulnerability/GO-2026-5559","summary":"OAuth2 Proxy has an Authentication Bypass via Fragment Confusion in skip_auth_routes and skip_auth_regex in github.com/oauth2-proxy/oauth2-proxy","modified":"2026-06-25T23:11:28.958923022Z","packages":[{"ecosystem":"Go","name":"github.com/oauth2-proxy/oauth2-proxy","purl":"pkg:golang/github.com/oauth2-proxy/oauth2-proxy","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/oauth2-proxy/oauth2-proxy/v7","purl":"pkg:golang/github.com/oauth2-proxy/oauth2-proxy/v7","ranges":[">=7.5.0 <7.15.2"],"fixed":["7.15.2"]}]}],"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."]}