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CVE-2020-3561

Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software WebVPN CRLF Injection Vulnerability

MEDIUM
4.7
CVSS Score
Published: October 21, 2020 at 06:41 PM UTC
Updated: August 11, 2026 at 07:37 PM UTC
2 products affected across 1 vendorAdaptive Security ApplianceSecure Firewall Threat Defense

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Severity
MEDIUM4.7
Exploit prediction
EPSS 1%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Adaptive Security Appliance· Cisco
95%
v < 9.6.4.359.10.0 ≤ v < 9.10.1.439.12.0 ≤ v < 9.12.3.99.13.0 ≤ v < 9.13.1.109.14.0 ≤ v < 9.14.1.109.8.0 ≤ v < 9.8.4.209.9.0 ≤ v < 9.9.2.80
Affected range stops below 9.10.1.43, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.12.3.9, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.13.1.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.14.1.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.6.4.35, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.8.4.20, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.9.2.80, so it looks safe — our inference, not a vendor statement
Secure Firewall Threat Defense· Cisco
95%
v < 6.3.0.66.4.0 ≤ v < 6.4.0.106.5.0 ≤ v < 6.5.0.56.6.0 ≤ v < 6.6.1

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

Vendor Advisoryx_refsource_CISCO
Source: [email protected]
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-crlf-inj-BX9uRwSn

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.7MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-93CWE-74

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