CVE-2021-1504

Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services VPN Denial of Service Vulnerabilities

HIGH
7.5
CVSS Score
Published: April 29, 2021 at 05:31 PM UTC
Updated: August 11, 2026 at 07:33 PM UTC
2 products affected across 1 vendorAdaptive Security ApplianceSecure Firewall Threat Defense

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Severity
HIGH7.5
Exploit prediction
EPSS 2%
SSVC
No known exploit

Description

Multiple vulnerabilities in Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. These vulnerabilities are due to lack of proper input validation of the HTTPS request. An attacker could exploit these vulnerabilities by sending a crafted HTTPS request to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Note: This vulnerability affects only specific AnyConnect and WebVPN configurations. For more information, see the Vulnerable Products section.

Affected

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

9.10 ≤ v < 9.12.4.109.13 ≤ v < 9.13.1.219.14 ≤ v < 9.14.2.49.15 ≤ v < 9.15.1.79.7 ≤ v < 9.8.4.359.9 ≤ v < 9.9.2.85
Affected range stops below 9.12.4.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.13.1.21, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.14.2.4, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.15.1.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.8.4.35, so it looks safe — our inference, not a vendor statement
Affected range stops below 9.9.2.85, so it looks safe — our inference, not a vendor statement
6.5.0 ≤ v < 6.6.46.7.0 ≤ v < 6.7.0.1

Remediation

No guide yet

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

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

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

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-787

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