{"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": "2026-06-24T14:26:28.296Z"}, "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"}}]}}

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{"bugzilla": {"description": "github.com/caddyserver/caddy: Caddy: Remote client can inject or override identity headers via header normalization", "id": "2491907", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2491907"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.1", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "status": "draft"}, "cwe": "CWE-444", "details": ["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."], "name": "CVE-2026-52845", "package_state": [{"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "caddy", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-06-23T17:52:01Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-52845\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-52845\nhttps://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2.11.4)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "caddy", "source": "cna", "vendor": "caddyserver"}, "product": "caddy", "vendor": "caddyserver"}], "created": "2026-06-23T22:00:09.250556+00:00", "updated": "2026-06-24T10:30:14.689407+00:00", "vendors": ["caddyserver", "caddyserver$PRODUCT$caddy"]}