CVE-2022-20866: A vulnerability in the handling of RSA keys on devices running Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FT...

Description

A vulnerability in the handling of RSA keys on devices running Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to retrieve an RSA private key. This vulnerability is due to a logic error when the RSA key is stored in memory on a hardware platform that performs hardware-based cryptography. An attacker could exploit this vulnerability by using a Lenstra side-channel attack against the targeted device. A successful exploit could allow the attacker to retrieve the RSA private key. The following conditions may be observed on an affected device: This vulnerability will apply to approximately 5 percent of the RSA keys on a device that is running a vulnerable release of Cisco ASA Software or Cisco FTD Software; not all RSA keys are expected to be affected due to mathematical calculations applied to the RSA key. The RSA key could be valid but have specific characteristics that make it vulnerable to the potential leak of the RSA private key. If an attacker obtains the RSA private key, they could use the key to impersonate a device that is running Cisco ASA Software or Cisco FTD Software or to decrypt the device traffic. See the Indicators of Compromise section for more information on the detection of this type of RSA key. The RSA key could be malformed and invalid. A malformed RSA key is not functional, and a TLS client connection to a device that is running Cisco ASA Software or Cisco FTD Software that uses the malformed RSA key will result in a TLS signature failure, which means a vulnerable software release created an invalid RSA signature that failed verification. If an attacker obtains the RSA private key, they could use the key to impersonate a device that is running Cisco ASA Software or Cisco FTD Software or to decrypt the device traffic.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

16.65%

96.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cisco	Adaptive Security Appliance Software	>= 9.16.0, < 9.16.3.19
Cisco	Adaptive Security Appliance Software	>= 9.17.0, < 9.17.1.13
Cisco	Adaptive Security Appliance Software	>= 9.18.0, < 9.18.2
Cisco	Firepower Threat Defense	>= 7.0.0, < 7.0.4
Cisco	Firepower Threat Defense	>= 7.1.0, < 7.2.0.1

References

Timeline

Published: Aug 10, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2022-20866?

A vulnerability in the handling of RSA keys on devices running Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to retrieve an RSA private key. This vulnerability is due to a logic error when the RSA key is stored in memory on a hardware platform that performs hardware-based cryptography. An attacker could exploit this vulnerability by using a Lenstra side-channel attack against the targeted device. A successful exploit could allow the attacker to retrieve the RSA private key. The following conditions may be observed on an affected device: This vulnerability will apply to approximately 5 percent of the RSA keys on a device that is running a vulnerable release of Cisco ASA Software or Cisco FTD Software; not all RSA keys are expected to be affected due to mathematical calculations applied to the RSA key. The RSA key could be valid but have specific characteristics that make it vulnerable to the potential leak of the RSA private key. If an attacker obtains the RSA private key, they could use the key to impersonate a device that is running Cisco ASA Software or Cisco FTD Software or to decrypt the device traffic. See the Indicators of Compromise section for more information on the detection of this type of RSA key. The RSA key could be malformed and invalid. A malformed RSA key is not functional, and a TLS client connection to a device that is running Cisco ASA Software or Cisco FTD Software that uses the malformed RSA key will result in a TLS signature failure, which means a vulnerable software release created an invalid RSA signature that failed verification. If an attacker obtains the RSA private key, they could use the key to impersonate a device that is running Cisco ASA Software or Cisco FTD Software or to decrypt the device traffic.

How severe is CVE-2022-20866?

CVE-2022-20866 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 16.65% probability of exploitation in the next 30 days.

How do I fix CVE-2022-20866?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.