{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-52845", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-08T18:41:27.724Z", "datePublished": "2026-06-23T17:52:01.871Z", "dateUpdated": "2026-07-15T00:46:09.498Z" }, "containers": { "cna": { "title": "Caddy: FastCGI header normalization bypass in `forward_auth copy_headers`", "problemTypes": [ { "descriptions": [ { "cweId": "CWE-287", "lang": "en", "description": "CWE-287: Improper Authentication", "type": "CWE" } ] }, { "descriptions": [ { "cweId": "CWE-290", "lang": "en", "description": "CWE-290: Authentication Bypass by Spoofing", "type": "CWE" } ] }, { "descriptions": [ { "cweId": "CWE-444", "lang": "en", "description": "CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')", "type": "CWE" } ] } ], "metrics": [ { "cvssV3_1": { "attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "version": "3.1" } } ], "references": [ { "name": "https://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g", "tags": [ "x_refsource_CONFIRM" ], "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g" } ], "affected": [ { "vendor": "caddyserver", "product": "caddy", "versions": [ { "version": "< 2.11.4", "status": "affected" } ] } ], "providerMetadata": { "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-06-23T17:52:01.871Z" }, "descriptions": [ { "lang": "en", "value": "Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, forward_auth copy_headers deletes the exact client-supplied identity header before copying the trusted value from the auth gateway. But when the request later goes through php_fastcgi, Caddy normalizes HTTP headers into CGI variables by replacing - with _. This lets a client send an underscore alias that survives the forward_auth delete step but becomes the same PHP/FastCGI variable. Result: a remote client can inject or sometimes override identity/group headers trusted by PHP/FastCGI applications behind Caddy. This vulnerability is fixed in 2.11.4." } ], "source": { "advisory": "GHSA-f59h-q822-g45g", "discovery": "UNKNOWN" } }, "adp": [ { "references": [ { "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g", "tags": [ "exploit" ] } ], "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-06-24T14:25:18.472130Z", "id": "CVE-2026-52845", "options": [ { "Exploitation": "poc" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-24T14:26:28.296Z" } }, { "affected": [ { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:hummingbird:1" ], "defaultStatus": "unaffected", "packageName": "caddy", "product": "Red Hat Hardened Images", "vendor": "Red Hat" } ], "datePublic": "2026-06-23T17:52:01.871Z", "descriptions": [ { "lang": "en", "value": "A flaw was found in Caddy, an extensible server platform. A remote attacker can exploit a vulnerability in the `forward_auth` `copy_headers` functionality. This occurs because Caddy normalizes HTTP headers into Common Gateway Interface (CGI) variables by replacing hyphens with underscores, allowing a client to send an underscore alias that bypasses the header deletion step. This enables the remote attacker to inject or override identity and group headers trusted by PHP/FastCGI applications operating behind Caddy." } ], "metrics": [ { "other": { "content": { "namespace": "https://access.redhat.com/security/updates/classification/", "value": "Important" }, "type": "Red Hat severity rating" } }, { "cvssV3_1": { "attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "version": "3.1" }, "format": "CVSS" } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-444", "description": "Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')", "lang": "en", "type": "CWE" } ] } ], "references": [ { "tags": [ "vdb-entry", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/security/cve/CVE-2026-52845" }, { "name": "RHBZ#2491907", "tags": [ "issue-tracking", "x_refsource_REDHAT" ], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2491907" }, { "tags": [ "x_sadp-csaf-vex" ], "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52845.json" } ], "timeline": [ { "lang": "en", "time": "2026-06-23T19:02:21.968Z", "value": "Reported to Red Hat." }, { "lang": "en", "time": "2026-06-23T17:52:01.871Z", "value": "Made public." } ], "title": "github.com/caddyserver/caddy: Caddy: Remote client can inject or override identity headers via header normalization", "x_adpType": "supplier", "x_generator": { "engine": "sadp-cli 1.0.0" }, "providerMetadata": { "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "shortName": "redhat-SADP", "dateUpdated": "2026-07-15T00:46:09.498Z" } } ] } }