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CVE-2026-52845

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 opera
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:2c85c07aa46a69319c95de48b79f9820af78140d3417c4df0f6e41f62f742a6f
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
2

Preserved source conflicts

No provider value was silently selected as the winner.

affected · 2 assertions

{"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"}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/affected/0

{"product":"caddy","vendor":"caddyserver","versions":[{"status":"affected","version":"< 2.11.4"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/affected/0
cwe · 4 assertions

{"cweId":"CWE-287","description":"CWE-287: Improper Authentication","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-444","description":"Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/problemTypes/0/descriptions/0

{"cweId":"CWE-444","description":"CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/problemTypes/2/descriptions/0

{"cweId":"CWE-290","description":"CWE-290: Authentication Bypass by Spoofing","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/problemTypes/1/descriptions/0

Affected products and versions

2 source assertions
{"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"}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/affected/0
{"product":"caddy","vendor":"caddyserver","versions":[{"status":"affected","version":"< 2.11.4"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/affected/0

Provider-owned CVSS observations

2 source assertions
{"metric":{"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"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/metrics/0/cvssV3_1
{"metric":{"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"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/metrics/1/cvssV3_1

CWE assertions

4 source assertions
{"cweId":"CWE-287","description":"CWE-287: Improper Authentication","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-444","description":"Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/problemTypes/0/descriptions/0
{"cweId":"CWE-444","description":"CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/problemTypes/2/descriptions/0
{"cweId":"CWE-290","description":"CWE-290: Authentication Bypass by Spoofing","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/problemTypes/1/descriptions/0

Source references

5 source assertions
{"tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-52845"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/references/0
{"name":"RHBZ#2491907","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2491907"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/references/1
{"tags":["exploit"],"url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/0/references/0
{"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"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/cna/references/0
{"tags":["x_sadp-csaf-vex"],"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52845.json"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:c4df388eb60c23edb6c862e4e820ee2dc8531116bbbe7bf6ce0f9d3271fd85de · sha256:dfda9d1c4705ef64… · /containers/adp/1/references/2

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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