{"id":"EUVD-2026-65061","enisaUuid":"06854951-af43-3bed-8752-9add2f1be558","description":"OAuth2 Proxy honours a client-supplied X-Forwarded-Uri header when deciding whether a request may skip authentication, because the guard added for CVE-2026-40575 is inert in the default reverse-proxy configuration. GetRequestURI in pkg/requests/util/util.go prefers that header over the real request URI whenever CanTrustForwardedHeaders returns true, and isAllowedPath in oauthproxy.go matches the skip_auth_routes and skip_auth_regex allow list against the resulting path. CanTrustForwardedHeaders in pkg/apis/middleware/scope.go grants that trust when the caller\u0027s address is in the trusted proxy set, and buildTrustedProxyNetSet falls back to defaultTrustedProxyIPs, which is 0.0.0.0/0 and ::/0, whenever reverse proxy mode is enabled without trusted_proxy_ip configured. Every client is therefore treated as a trusted proxy. An unauthenticated attacker can request a protected upstream path while setting X-Forwarded-Uri to a value matching an allow-listed route, so the skip-auth decision is made against the spoofed value while the upstream receives the protected path unchanged.","datePublished":"Aug 24, 2026, 5:55:39 PM","dateUpdated":"Oct 8, 2026, 3:25:05 PM","baseScore":9.3,"baseScoreVersion":"4.0","baseScoreVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","references":"https://github.com/oauth2-proxy/oauth2-proxy\nhttps://github.com/oauth2-proxy/oauth2-proxy/issues/3506\nhttps://github.com/oauth2-proxy/oauth2-proxy/blob/v7.15.4/pkg/apis/middleware/scope.go\nhttps://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x\nhttps://www.vulncheck.com/advisories/oauth2-proxy-through-authentication-bypass-via-x-forwarded-uri-under-the-default-trusted-proxy-set\n","aliases":"CVE-2026-76835\nGHSA-vvqv-7vrf-88vh\n","assigner":"VulnCheck","epss":0.45,"enisaIdProduct":[{"id":"b4e336c6-3679-37df-bbf1-a83f6dd066ad","product":{"name":"oauth2-proxy","vendor":{"name":"oauth2-proxy"}},"product_version":"7.15.2 ≤7.15.4"}],"enisaIdVendor":[{"id":"2d430d34-5885-3184-adab-035680b1e121","vendor":{"name":"oauth2-proxy"}}],"enisaIdVulnerability":[{"id":"5b6fed5e-25e2-3f3b-9832-737890a9a087","vulnerability":{"id":"CVE-2026-76835","description":"OAuth2 Proxy honours a client-supplied X-Forwarded-Uri header when deciding whether a request may skip authentication, because the guard added for CVE-2026-40575 is inert in the default reverse-proxy configuration. GetRequestURI in pkg/requests/util/util.go prefers that header over the real request URI whenever CanTrustForwardedHeaders returns true, and isAllowedPath in oauthproxy.go matches the skip_auth_routes and skip_auth_regex allow list against the resulting path. CanTrustForwardedHeaders in pkg/apis/middleware/scope.go grants that trust when the caller\u0027s address is in the trusted proxy set, and buildTrustedProxyNetSet falls back to defaultTrustedProxyIPs, which is 0.0.0.0/0 and ::/0, whenever reverse proxy mode is enabled without trusted_proxy_ip configured. Every client is therefore treated as a trusted proxy. An unauthenticated attacker can request a protected upstream path while setting X-Forwarded-Uri to a value matching an allow-listed route, so the skip-auth decision is made against the spoofed value while the upstream receives the protected path unchanged.","datePublished":"Aug 24, 2026, 5:55:39 PM","dateUpdated":"Oct 8, 2026, 3:25:05 PM","status":"PUBLISHED","baseScore":9.3,"baseScoreVersion":"4.0","baseScoreVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","references":"https://github.com/oauth2-proxy/oauth2-proxy\nhttps://github.com/oauth2-proxy/oauth2-proxy/issues/3506\nhttps://github.com/oauth2-proxy/oauth2-proxy/blob/v7.15.4/pkg/apis/middleware/scope.go\nhttps://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x\nhttps://www.vulncheck.com/advisories/oauth2-proxy-through-authentication-bypass-via-x-forwarded-uri-under-the-default-trusted-proxy-set\n","enisa_id":"EUVD-2026-65061\n","assigner":"VulnCheck","epss":0.45,"dataProcessed":"Oct 28, 2026, 7:14:28 AM","vulnerabilityProduct":[{"id":"d6400cf6-9c2d-3969-9830-9bd126133569","product":{"name":"oauth2-proxy","vendor":{"name":"oauth2-proxy"}},"product_version":"7.15.2 ≤7.15.4"}],"vulnerabilityVendor":[{"id":"02351069-3610-37d3-8de5-311d8ca9cbb4","vendor":{"name":"oauth2-proxy"}}]}},{"id":"bf8879b3-19bc-31b0-ab27-7ffc8c201088","vulnerability":{"id":"GHSA-vvqv-7vrf-88vh","description":"OAuth2 Proxy honours a client-supplied X-Forwarded-Uri header when deciding whether a request may skip authentication, because the guard added for CVE-2026-40575 is inert in the default reverse-proxy configuration. GetRequestURI in pkg/requests/util/util.go prefers that header over the real request URI whenever CanTrustForwardedHeaders returns true, and isAllowedPath in oauthproxy.go matches the skip_auth_routes and skip_auth_regex allow list against the resulting path. CanTrustForwardedHeaders in pkg/apis/middleware/scope.go grants that trust when the caller\u0027s address is in the trusted proxy set, and buildTrustedProxyNetSet falls back to defaultTrustedProxyIPs, which is 0.0.0.0/0 and ::/0, whenever reverse proxy mode is enabled without trusted_proxy_ip configured. Every client is therefore treated as a trusted proxy. An unauthenticated attacker can request a protected upstream path while setting X-Forwarded-Uri to a value matching an allow-listed route, so the skip-auth decision is made against the spoofed value while the upstream receives the protected path unchanged.","datePublished":"Aug 24, 2026, 6:31:57 PM","dateUpdated":"Aug 24, 2026, 6:31:58 PM","baseScore":0.0,"references":"https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-76835\nhttps://github.com/oauth2-proxy/oauth2-proxy/issues/3506\nhttps://github.com/oauth2-proxy/oauth2-proxy\nhttps://github.com/oauth2-proxy/oauth2-proxy/blob/v7.15.4/pkg/apis/middleware/scope.go\nhttps://www.vulncheck.com/advisories/oauth2-proxy-through-authentication-bypass-via-x-forwarded-uri-under-the-default-trusted-proxy-set\n","enisa_id":"EUVD-2026-65061\n","aliases":"GHSA-vvqv-7vrf-88vh\nCVE-2026-76835\n","epss":0.0,"dataProcessed":"Oct 25, 2026, 1:59:46 AM","vulnerabilityProduct":[],"vulnerabilityVendor":[]}}],"enisaIdAdvisory":[{"id":"1b72ee7b-2684-3bee-8281-ccf19142c1ac","advisory":{"id":"RHSA-2026:74536","description":"Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update","summary":"An update for Red Hat Hardened Images RPMs is now available.","datePublished":"Oct 1, 2026, 4:26:14 PM","dateUpdated":"Oct 25, 2026, 6:59:03 AM","baseScore":0.0,"references":"https://access.redhat.com/errata/RHSA-2026:74536\nhttps://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_74536.json\n","aliases":"CVE-2026-56851\nCVE-2026-76835\n","source":{"id":9,"name":"csaf_redhat"},"advisoryProduct":[{"id":"4affdabb-5071-316d-b86c-cf1b4cbcc8d5","product":{"name":"oauth2-proxy-0:7.15.5-0.1.hum1@x86_64","vendor":{"name":"Red Hat"}}},{"id":"a63ea481-b555-3455-bbb0-8c1493c119e7","product":{"name":"Red Hat Hardened Images","vendor":{"name":"Red Hat"}}},{"id":"dd1d5820-2c02-3f02-b6a7-c225f0f7a590","product":{"name":"oauth2-proxy-0:7.15.5-0.1.hum1@aarch64","vendor":{"name":"Red Hat"}}},{"id":"e5e694ec-813d-3f5f-9fc6-8a7060aed1f5","product":{"name":"oauth2-proxy-0:7.15.5-0.1.hum1@src","vendor":{"name":"Red Hat"}}}]}}]}