{"id":"CVE-2018-1000164","aliases":["GHSA-32pc-xphx-q4f6","PYSEC-2018-55"],"title":"Gunicorn contains Improper Neutralization of CRLF sequences in HTTP headers","summary":"Gunicorn contains Improper Neutralization of CRLF sequences in HTTP headers","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","vendor":"gunicorn","product":"gunicorn","ecosystem":"pip","affected":["gunicorn < 19.5.0"],"patched":["gunicorn 19.5.0"],"published":"2018-07-12","updated":"2026-09-08","sourceUpdated":"2026-09-08T15:46:56.599254Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-32pc-xphx-q4f6","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2018-1000164"},{"url":"https://github.com/benoitc/gunicorn/issues/1227"},{"url":"https://github.com/benoitc/gunicorn/commit/1e10a02e73c87dfadc394b361af33864d0e59e24"},{"url":"https://epadillas.github.io/2018/04/02/http-header-splitting-in-gunicorn-19.4.5"},{"url":"https://github.com/benoitc/gunicorn"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/gunicorn/PYSEC-2018-55.yaml"},{"url":"https://lists.debian.org/debian-lts-announce/2018/04/msg00022.html"},{"url":"https://usn.ubuntu.com/4022-1"},{"url":"https://www.debian.org/security/2018/dsa-4186"},{"url":"https://github.com/advisories/GHSA-32pc-xphx-q4f6"}],"tags":["osv","pip","ghsa"],"epss":0.02503,"epssPercentile":0.8391,"cwe":["CWE-93"],"ingestedAt":"2026-09-08T16:34:19.230Z","slug":"CVE-2018-1000164","body":"## Overview\n\ngunicorn version 19.4.5 contains a CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers vulnerability in \"process_headers\" function in \"gunicorn/http/wsgi.py\" that can result in an attacker causing the server to return arbitrary HTTP headers. This vulnerability appears to have been fixed in 19.5.0.\n\n## Affected packages\n\n- `gunicorn < 19.5.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `gunicorn 19.5.0`","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":41.3,"likelihood":0.5,"exploitation":0,"ransomware":0},"changes":[]}