{"id":"GHSA-q2qj-628g-vhfw","aliases":["CVE-2023-30536"],"title":"Insecure header validation in slim/psr7","titleSource":"OSV","descriptionSource":"OSV","declaredSeverity":"MODERATE","description":"### Impact\n\nAn attacker could sneak in a newline (`\\n`) into both the header names and values. While the specification states that `\\r\\n\\r\\n` is used to terminate the header list, many servers in the wild will also accept `\\n\\n`. An attacker that is able to control the header names that are passed to Slilm-Psr7 would be able to intentionally craft invalid messages, possibly causing application errors or invalid HTTP requests being sent out with an PSR-18 HTTP client. The latter might present a denial of service vector if a remote service’s web application firewall bans the application due to the receipt of malformed requests.\n\n### Patches\n\nThe issue is patched in 1.6.1, 1.5.1, and 1.4.1.\n\n### Workarounds\n\nIn Slim-Psr7 prior to 1.6.1, 1.5.1, and 1.4.1, validate HTTP header keys and/or values, and if using user-supplied values, filter them to strip off leading or trailing newline characters before calling withHeader().\n\n### Acknowledgments\n\nWe are very grateful to and thank <a href=\"https://gjcampbell.co.uk/\">Graham Campbell</a> for reporting and working with us on this issue.\n\n### References\n\n* Guzzle: CVE-2023-29197, with advisory GHSA-wxmh-65f7-jcvw\n* Laminas Diactoros: CVE-2023-29530, with advisory GHSA-xv3h-4844-9h36\n* https://www.rfc-editor.org/rfc/rfc7230#section-3.2.4","severity":"medium","score":6.5,"published":"2023-04-18T22:20:42.000Z","modified":"2026-09-10T03:50:01.161Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Packagist","name":"slim/psr7","sources":[{"name":"OSV · GHSA-q2qj-628g-vhfw","url":"https://osv.dev/vulnerability/GHSA-q2qj-628g-vhfw"}],"ranges":[{"events":[{"introduced":"1.6"},{"fixed":"1.6.1"}],"type":"ECOSYSTEM"}],"versions":["1.6"],"fixed":["1.6.1"]},{"ecosystem":"Packagist","name":"slim/psr7","sources":[{"name":"OSV · GHSA-q2qj-628g-vhfw","url":"https://osv.dev/vulnerability/GHSA-q2qj-628g-vhfw"}],"ranges":[{"events":[{"introduced":"1.5"},{"fixed":"1.5.1"}],"type":"ECOSYSTEM"}],"versions":["1.5"],"fixed":["1.5.1"]},{"ecosystem":"Packagist","name":"slim/psr7","sources":[{"name":"OSV · GHSA-q2qj-628g-vhfw","url":"https://osv.dev/vulnerability/GHSA-q2qj-628g-vhfw"}],"ranges":[{"events":[{"introduced":"0"},{"fixed":"1.4.1"}],"type":"ECOSYSTEM"}],"versions":["0.1.0","0.2.0","0.3.0","0.4.0","0.5.0","0.6","1.0.0","1.1.0","1.2.0","1.3.0","1.4"],"fixed":["1.4.1"]}],"sourceAffected":[],"references":["https://github.com/slimphp/Slim-Psr7/security/advisories/GHSA-q2qj-628g-vhfw","https://nvd.nist.gov/vuln/detail/CVE-2023-30536","https://github.com/slimphp/Slim-Psr7/issues/284#issuecomment-1541328898","https://github.com/slimphp/Slim-Psr7/commit/ed1d553225dd190875d8814c47460daed4b550bb","https://github.com/slimphp/Slim-Psr7","https://github.com/slimphp/Slim-Psr7/releases/tag/1.4.1","https://github.com/slimphp/Slim-Psr7/releases/tag/1.5.1","https://github.com/slimphp/Slim-Psr7/releases/tag/1.6.1","https://www.rfc-editor.org/rfc/rfc7230#section-3.2.4"],"sources":[{"name":"OSV","id":"GHSA-q2qj-628g-vhfw","modified":"2026-09-10T03:50:01.161824075Z","url":"https://osv.dev/vulnerability/GHSA-q2qj-628g-vhfw"}],"assessments":[{"source":"OSV","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L","score":6.5}],"products":[],"remediation":[],"kev":{"status":"not-listed","checkedAt":"2026-10-29T00:50:31.383Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}