{"cve":"CVE-2021-43437","nvd":{"published":"2021-12-20T20:15:07.660","modified":"2026-06-17T04:10:57.690","status":"Modified","description":"In sourcecodetester Engineers Online Portal as of 10-21-21, an attacker can manipulate the Host header as seen by the web application and cause the application to behave in unexpected ways. Very often multiple websites are hosted on the same IP address. This is where the Host Header comes in. This header specifies which website should process the HTTP request. The web server uses the value of this header to dispatch the request to the specified website. Each website hosted on the same IP address is called a virtual host. And It's possible to send requests with arbitrary Host Headers to the first virtual host.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-74"],"references":["https://medium.com/%40mayhem7999/cve-2021-43437-5c5e3b977e84","https://portswigger.net/web-security/host-header","https://medium.com/%40mayhem7999/cve-2021-43437-5c5e3b977e84","https://portswigger.net/web-security/host-header"],"products":["engineers_online_portal_project:engineers_online_portal"],"source":"nvd","synced_at":"2026-10-19T21:25:41.256909649+00:00"},"epss":{"cve":"CVE-2021-43437","score":0.01268,"percentile":0.69775,"date":"2026-11-01"},"kev":null,"osv":[],"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."]}