CVE-2024-20337
Cisco Secure Client 4.10.04065 – 4.10.08025
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:NSummary
CVE-2024-20337 is a high-severity CRLF Injection (CWE-93) vulnerability in Cisco Secure Client. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Content Injection (T1659); ranked in the top 2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-18052
Vulnerability Data
A vulnerability in the SAML authentication process of Cisco Secure Client could allow an unauthenticated, remote attacker to conduct a carriage return line feed (CRLF) injection attack against a user. This vulnerability is due to insufficient validation of user-supplied input.…
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An attacker could exploit this vulnerability by persuading a user to click a crafted link while establishing a VPN session. A successful exploit could allow the attacker to execute arbitrary script code in the browser or access sensitive, browser-based information, including a valid SAML token. The attacker could then use the token to establish a remote access VPN session with the privileges of the affected user. Individual hosts and services behind the VPN headend would still need additional credentials for successful access.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V4.2.4
Mitigating Controls (NIST 800-53 r5) AI
Input validation directly stops untrusted data containing CRLF sequences from reaching the component that treats CRLF as a delimiter.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input neutralization and validation to block CRLF injection.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect CRLF flaws but does not itself implement the neutralization.
Secure development lifecycle mandates input validation and output encoding that directly prevents CRLF injection.
Application security requirements include rules for neutralizing special characters such as CRLF in inputs.
Secure architecture principles encourage safe handling of untrusted data but do not prescribe specific CRLF controls.
Secure coding standards explicitly require neutralization of CRLF sequences, fully addressing this weakness.