{"cve":"CVE-2021-33037","nvd":{"published":"2021-07-12T15:15:08.400","modified":"2026-10-08T22:17:09.837","status":"Modified","description":"Apache Tomcat 10.0.0-M1 to 10.0.6, 9.0.0.M1 to 9.0.46 and 8.5.0 to 8.5.66 did not correctly parse the HTTP transfer-encoding request header in some circumstances leading to the possibility to request smuggling when used with a reverse proxy. Specifically: - Tomcat incorrectly ignored the transfer encoding header if the client declared it would only accept an HTTP/1.0 response; - Tomcat honoured the identify encoding; and - Tomcat did not ensure that, if present, the chunked encoding was the final encoding.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3},"cwes":["CWE-444"],"references":["https://kc.mcafee.com/corporate/index?page=content&id=SB10366","https://lists.apache.org/thread.html/r290aee55b72811fd19e75ac80f6143716c079170c5671b96932ed44b%40%3Ccommits.tomee.apache.org%3E","https://lists.apache.org/thread.html/r40f921575aee8d7d34e53182f862c45cbb8f3d898c9d4e865c2ec262%40%3Ccommits.tomee.apache.org%3E","https://lists.apache.org/thread.html/r612a79269b0d5e5780c62dfd34286a8037232fec0bc6f1a7e60c9381%40%3Cannounce.tomcat.apache.org%3E","https://lists.apache.org/thread.html/rc6ef52453bb996a98cb45442871a1db56b7c349939e45d829bf9ae37%40%3Ccommits.tomee.apache.org%3E"],"products":["apache:tomcat","apache:tomee","debian:debian_linux","mcafee:epolicy_orchestrator","oracle:agile_product_lifecycle_management","oracle:communications_cloud_native_core_policy","oracle:communications_cloud_native_core_service_communication_proxy","oracle:communications_diameter_signaling_router","oracle:communications_instant_messaging_server","oracle:communications_policy_management","oracle:communications_pricing_design_center","oracle:communications_session_report_manager","oracle:communications_session_route_manager","oracle:graph_server_and_client","oracle:healthcare_translational_research","oracle:hospitality_cruise_shipboard_property_management_system","oracle:instantis_enterprisetrack","oracle:managed_file_transfer","oracle:mysql_enterprise_monitor","oracle:sd-wan_edge","oracle:secure_global_desktop","oracle:utilities_testing_accelerator"],"source":"nvd","synced_at":"2026-10-19T21:21:13.713336758+00:00"},"epss":{"cve":"CVE-2021-33037","score":0.74667,"percentile":0.99498,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-4vww-mc66-62m6","url":"https://osv.dev/vulnerability/GHSA-4vww-mc66-62m6","summary":"HTTP Request Smuggling in Apache Tomcat","modified":"2024-03-11T18:16:20.683331Z","packages":[{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","purl":"pkg:maven/org.apache.tomcat/tomcat","ranges":[">=10.0.0-M1 <10.0.7"],"fixed":["10.0.7"]},{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","purl":"pkg:maven/org.apache.tomcat/tomcat","ranges":[">=9.0.0-M1 <9.0.48"],"fixed":["9.0.48"]},{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","purl":"pkg:maven/org.apache.tomcat/tomcat","ranges":[">=8.5.0 <8.5.68"],"fixed":["8.5.68"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}