{"cve":"CVE-2020-3561","nvd":{"published":"2020-10-21T19:15:17.793","modified":"2026-08-11T19:37:30.880","status":"Modified","description":"A vulnerability in the Clientless SSL VPN (WebVPN) of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to inject arbitrary HTTP headers in the responses of the affected system. The vulnerability is due to improper input sanitization. An attacker could exploit this vulnerability by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to conduct a CRLF injection attack, adding arbitrary HTTP headers in the responses of the system and redirecting the user to arbitrary websites.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N","score":4.7},"cwes":["CWE-74","CWE-93"],"references":["https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-crlf-inj-BX9uRwSn","https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-crlf-inj-BX9uRwSn"],"products":["cisco:adaptive_security_appliance","cisco:adaptive_security_appliance_software","cisco:secure_firewall_threat_defense"],"source":"nvd","synced_at":"2026-10-19T21:09:53.489947993+00:00"},"epss":{"cve":"CVE-2020-3561","score":0.01275,"percentile":0.69919,"date":"2026-10-31"},"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."]}