{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-76835",
        "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "state": "PUBLISHED",
        "assignerShortName": "VulnCheck",
        "dateReserved": "2026-08-19T20:34:00.154Z",
        "datePublished": "2026-08-24T17:55:39.829Z",
        "dateUpdated": "2026-08-24T17:55:39.829Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
                "shortName": "VulnCheck",
                "dateUpdated": "2026-08-24T17:55:39.829Z"
            },
            "datePublic": "2026-08-17T00:00:00.000Z",
            "title": "OAuth2 Proxy 7.15.2 through 7.15.4 Authentication Bypass via X-Forwarded-Uri Under the Default Trusted Proxy Set",
            "descriptions": [
                {
                    "lang": "en",
                    "value": "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's 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."
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-290",
                            "description": "Authentication Bypass by Spoofing",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "oauth2-proxy",
                    "product": "oauth2-proxy",
                    "defaultStatus": "unaffected",
                    "versions": [
                        {
                            "version": "7.15.2",
                            "lessThanOrEqual": "7.15.4",
                            "status": "affected",
                            "versionType": "semver"
                        }
                    ],
                    "repo": "https://github.com/oauth2-proxy/oauth2-proxy",
                    "packageURL": "pkg:golang/github.com/oauth2-proxy/oauth2-proxy"
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "7.15.2",
                                    "versionEndIncluding": "7.15.4"
                                }
                            ]
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "cvssV4_0": {
                        "version": "4.0",
                        "vectorString": "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",
                        "baseScore": 9.3,
                        "baseSeverity": "CRITICAL",
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "vulnIntegrityImpact": "HIGH",
                        "vulnAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "subAvailabilityImpact": "NONE"
                    }
                },
                {
                    "format": "CVSS",
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
                        "baseScore": 9.1,
                        "baseSeverity": "CRITICAL",
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "scope": "UNCHANGED",
                        "confidentialityImpact": "HIGH",
                        "integrityImpact": "HIGH",
                        "availabilityImpact": "NONE"
                    }
                }
            ],
            "references": [
                {
                    "url": "https://github.com/oauth2-proxy/oauth2-proxy",
                    "tags": [
                        "product"
                    ]
                },
                {
                    "url": "https://github.com/oauth2-proxy/oauth2-proxy/issues/3506",
                    "tags": [
                        "issue-tracking"
                    ]
                },
                {
                    "url": "https://github.com/oauth2-proxy/oauth2-proxy/blob/v7.15.4/pkg/apis/middleware/scope.go",
                    "tags": [
                        "technical-description"
                    ]
                },
                {
                    "url": "https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x",
                    "tags": [
                        "vendor-advisory"
                    ]
                },
                {
                    "name": "VulnCheck Advisory: OAuth2 Proxy 7.15.2 through 7.15.4 Authentication Bypass via X-Forwarded-Uri Under the Default Trusted Proxy Set",
                    "tags": [
                        "third-party-advisory"
                    ],
                    "url": "https://www.vulncheck.com/advisories/oauth2-proxy-through-authentication-bypass-via-x-forwarded-uri-under-the-default-trusted-proxy-set"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "George Chen",
                    "type": "finder"
                }
            ],
            "x_generator": {
                "engine": "vulncheck-endgame"
            }
        }
    }
}