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CVE-2020-3585

Cisco Firepower 1000 Series Bleichenbacher Attack Vulnerability

5.3 Medium

A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain access to sensitive information. The vulnerability is due to improper implementation of countermeasures against the Bleichenbacher attack for cipher suites that rely on RSA for key exchange. An attacker could exploit this vulnerability by sending crafted TLS messages to the device, which would act as an oracle and allow the attacker to carry out a chosen-ciphertext attack. A successful exploit could allow the attacker to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions to the affected device. To exploit this vulnerability, an attacker must be able to perform both of the following actions: Capture TLS traffic that is in transit between clients and the affected device Actively establish a considerable number of TLS connections to the affected device

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

1.27%Up 0.7 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 5.3

Cisco Firepower 1000 Series Bleichenbacher Attack Vulnerability

A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain access to sensitive information. The vulnerability is due to improper implementation of countermeasures against the Bleichenbacher attack for cipher suites that rely on RSA for key exchange. An attacker could exploit this vulnerability by sending crafted TLS messages to the device, which would act as an oracle and allow the attacker to carry out a chosen-ciphertext attack. A successful exploit could allow the attacker to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions to the affected device. To exploit this vulnerability, an attacker must be able to perform both of the following actions: Capture TLS traffic that is in transit between clients and the affected device Actively establish a considerable number of TLS connections to the affected device

Record
CVE-2020-3585
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-203
Updated
2026-11-02
EUVDEUVD-2020-24856 5.3

A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain access to sensitive information. The vulnerability is due to improper implementation of countermeasures against the Bleichenbacher attack for cipher suites that rely on RSA for key exchange. An attacker could exploit this vulnerability by sending crafted TLS messages to the device, which would act as an oracle and allow the attacker to carry out a chosen-ciphertext attack. A successful exploit could allow the attacker to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions to the affected device. To exploit this vulnerability, an attacker must be able to perform both of the following actions: Capture TLS traffic that is in transit between clients and the affected device Actively establish a considerable number of TLS connections to the affected device

Record
EUVD-2020-24856
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-w7hv-422j-p88g 3.7

A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco...

A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain access to sensitive information. The vulnerability is due to improper implementation of countermeasures against the Bleichenbacher attack for cipher suites that rely on RSA for key exchange. An attacker could exploit this vulnerability by sending crafted TLS messages to the device, which would act as an oracle and allow the attacker to carry out a chosen-ciphertext attack. A successful exploit could allow the attacker to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions to the affected device. To exploit this vulnerability, an attacker must be able to perform both of the following actions: Capture TLS traffic that is in transit between clients and the affected device Actively establish a considerable number of TLS connections to the affected device

Record
GHSA-w7hv-422j-p88g
CVSS 3.1
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-203
Updated
2026-11-02
NVD 5.3

A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain access to sensitive information. The vulnerability is due to improper implementation of countermeasures against the Bleichenbacher attack for cipher suites that rely on RSA for key exchange. An attacker could exploit this vulnerability by sending crafted TLS messages to the device, which would act as an oracle and allow the attacker to carry out a chosen-ciphertext attack. A successful exploit could allow the attacker to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions to the affected device. To exploit this vulnerability, an attacker must be able to perform both of the following actions: Capture TLS traffic that is in transit between clients and the affected device Actively establish a considerable number of TLS connections to the affected device

Record
CVE-2020-3585
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS 3.1
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:P/I:N/A:N
Weakness
CWE-203
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
facts
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-3585 is a medium vulnerability (CVSS 5.3) in Cisco Adaptive Security Appliance (asa) Software, published October 21, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.27%, the 69th percentile. No source names a fixed version.

References

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