{"id":"CVE-2021-40438","aliases":["BIT-apache-2021-40438"],"url":"https://o3.security/vulnerability/CVE-2021-40438","summary":null,"details":"A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.","published":"2021-09-16T15:15:07.633Z","modified":"2026-08-07T03:30:17.209832720Z","cvss":{"score":9,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H"},"epss":{"score":0.99999,"percentile":0.99997,"asOf":"2026-09-05"},"cisaKev":null,"exploitsKnown":13,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40438"},{"type":"ADVISORY","url":"https://cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf"},{"type":"ADVISORY","url":"https://httpd.apache.org/security/vulnerabilities_24.html"},{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2021/10/msg00001.html"},{"type":"ADVISORY","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/"},{"type":"ADVISORY","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/"},{"type":"ADVISORY","url":"https://security.gentoo.org/glsa/202208-20"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20211008-0004/"},{"type":"ADVISORY","url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQ"},{"type":"ADVISORY","url":"https://www.debian.org/security/2021/dsa-4982"},{"type":"ADVISORY","url":"https://www.tenable.com/security/tns-2021-17"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpuapr2022.html"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpujan2022.html"},{"type":"ARTICLE","url":"https://lists.apache.org/thread.html/r210807d0bb55f4aa6fbe1512be6bcc4dacd64e84940429fba329967a%40%3Cusers.httpd.apache.org%3E"},{"type":"ARTICLE","url":"https://lists.apache.org/thread.html/r2eb200ac1340f69aa22af61ab34780c531d110437910cb9c0ece3b37%40%3Cbugs.httpd.apache.org%3E"},{"type":"ARTICLE","url":"https://lists.apache.org/thread.html/r3925e167d5eb1c75def3750c155d753064e1d34a143028bb32910432%40%3Cusers.httpd.apache.org%3E"},{"type":"ARTICLE","url":"https://lists.apache.org/thread.html/r61fdbfc26ab170f4e6492ef3bd5197c20b862ce156e9d5a54d4b899c%40%3Cusers.httpd.apache.org%3E"},{"type":"ARTICLE","url":"https://lists.apache.org/thread.html/r82838efc5fa6fc4c73986399c9b71573589f78b31846aff5bd9b1697%40%3Cusers.httpd.apache.org%3E"},{"type":"ARTICLE","url":"https://lists.apache.org/thread.html/r82c077663f9759c7df5a6656f925b3ee4f55fcd33c889ba7cd687029%40%3Cusers.httpd.apache.org%3E"},{"type":"ARTICLE","url":"https://lists.apache.org/thread.html/rf6954e60b1c8e480678ce3d02f61b8a788997785652e9557a3265c00%40%3Cusers.httpd.apache.org%3E"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T03:30:17.209832720Z"}}