CVE-2026-76835

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Source
https://cve.org/CVERecord?id=CVE-2026-76835
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-76835.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-76835
Aliases
Published
2026-08-24T17:55:39.829Z
Modified
2026-08-27T11:47:27.457076646Z
Severity
  • 9.3 (Critical) CVSS_V4 - 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 CVSS Calculator
Summary
OAuth2 Proxy 7.15.2 through 7.15.4 Authentication Bypass via X-Forwarded-Uri Under the Default Trusted Proxy Set
Details

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 skipauthroutes and skipauthregex 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 trustedproxyip 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.

Database specific 
{
    "cwe_ids": [
        "CWE-290"
    ],
    "cna_assigner": "VulnCheck",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76835.json"
}
References

Affected packages

Git / github.com/oauth2-proxy/oauth2-proxy

Affected ranges

Type
GIT
Repo
https://github.com/oauth2-proxy/oauth2-proxy
Events
Introduced
5961fd99b42c3625b8ef08690d38be5cb37f44b0
Last affected
81ff034fe2ff3246e670c694b02e3267d1ae46bc
Database specific
Show details 
{
    "source": "AFFECTED_FIELD",
    "extracted_events": [
        {
            "introduced": "7.15.2"
        },
        {
            "last_affected": "7.15.4"
        }
    ]
}

Affected versions

v7.*
v7.15.2
v7.15.3
v7.15.4

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-76835.json"