CVE-2021-1422

mediumpriority · track · 31EPSS 0.012 · 68 %ileEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.20% (68th) EPSS

CVSS 6.8 · medium

Is it mine?

15 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · fstec_bdu · cisco_csaf

EPSS · scored 2026-10-27

A vulnerability in the software cryptography module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker or an unauthenticated attacker in a man-in-the-middle position to cause an unexpected reload of the device that results in a denial of service (DoS) condition. The vulnerability is due to a logic error in how the software cryptography module handles specific types of decryption errors. An attacker could exploit this vulnerability by sending malicious packets over an established IPsec connection. A successful exploit could cause the device to crash, forcing it to reload. Important: Successful exploitation of this vulnerability would not cause a compromise of any encrypted data. Note: This vulnerability affects only Cisco ASA Software Release 9.16.1 and Cisco FTD Software Release 7.0.0.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

FixedCisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Adaptive Security Virtual Appliance (ASAv)cisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 1000 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 2100 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 4100 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 9000 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 1000 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 2100 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 4100 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 9000 Seriescisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com
FixedCisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Secure Firewall Threat Defense Virtualcisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com

cvss

Technical severity, 0–10. One row per scoring source.

7.7

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.8–7.7

v2.06.8mediumAV:N/AC:L/Au:S/C:N/I:N/A:Cprimary · NVD / NIST USexploitability 8 · impact 6.9

v3.17.7highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.1 · impact 4

v3.17.7highAV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

v3.17.7highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:Hsecondary · ENISA EU

v3.17.7highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:Hsecondary · psirt@cisco.com USexploitability 3.1 · impact 4

v3.17.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.17.7highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:Hsecondary · Cisco PSIRT US

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-617USprimaryCWE-617US

affected products (15)

Products and version ranges known to be affected.

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Adaptive Security Virtual Appliance (ASAv)all versionscisco_csafUS
Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 1000 Seriesall versionscisco_csafUS
Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 2100 Seriesall versionscisco_csafUS
Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 4100 Seriesall versionscisco_csafUS
Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 when installed on Cisco Firepower 9000 Seriesall versionscisco_csafUS
Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 1000 Seriesall versionscisco_csafUS
Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 2100 Seriesall versionscisco_csafUS
Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 4100 Seriesall versionscisco_csafUS
Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Firepower 9000 Seriesall versionscisco_csafUS
Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 when installed on Cisco Secure Firewall Threat Defense Virtualall versionscisco_csafUS
Cisco Cisco Adaptive Security Appliance (ASA) Software≤ n/aenisa_euvdEU
Cisco Systems Inc. Adaptive Security Appliance≤ 9.16.1fstec_bduRU
Cisco Systems Inc. Firepower Threat Defense≤ 7.0.0fstec_bduRU
cisco adaptive security appliance software= 9.16.1nvdUScpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
cisco secure firewall threat defense= 7.0.0.0nvdUScpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

cisco-sa-asa-ftd-ipsec-dos-TFKQbgWCCisco Adaptive Security Appliance Software Release 9.16.1 and Cisco Firepower Threat Defense Software Release 7.0.0 IPsec Denial of Service Vulnerability2021-07-15csaf · cisco_csafUS
A vulnerability in the software cryptography module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker or an unauthenticated attacker in a man-in-the-middle position to cause an unexpected reload of the device that results in a denial of service (DoS) condition. The vulnerability is due to a logic error in how the software cryptography module handles specific types of decryption errors. An attacker could exploit this vulnerability by sending malicious packets over an established IPsec connection. A successful exploit could cause the device to crash, forcing it to reload. Important: Successful exploitation of this vulnerability would not cause a compromise of any encrypted data. Note: This vulnerability affects only Cisco ASA Software Release 9.16.1 and Cisco FTD Software Release 7.0.0. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cisco_csaf nvd NVD CVE.org MITRE

published 2021-07-16modified 2026-08-11

related (1,031)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2015-5477US	high7.8OT critical	99.6% (100th)	KEV	2015-07-29
named in ISC BIND 9.x before 9.9.7-P2 and 9.10.x before 9.10.2-P3 allows remote attackers to cause a denial of service (REQUIRE assertion failure and daemon exit) via TKEY queries.
CVE-2016-2776US	high7.5	89.5% (100th)	Exploit	2016-09-28
buffer.c in named in ISC BIND 9 before 9.9.9-P3, 9.10.x before 9.10.4-P3, and 9.11.x before 9.11.0rc3 does not properly construct responses, which allows remote attackers to cause…
CVE-2021-25216US	critical9.8	83.0% (100th)	—	2021-04-29
In BIND 9.5.0 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.11.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND Supported Preview Edition, as well as release versions 9.…
CVE-2020-8617US	medium5.9	93.4% (100th)	Exploit	2020-05-19
Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG…
CVE-2018-5740US	high7.5	59.6% (99th)	Exploit	2019-01-16
"deny-answer-aliases" is a little-used feature intended to help recursive server operators protect end users against DNS rebinding attacks, a potential method of circumventing the…

+1026 more

references (6)

External citations — patches, advisories, analysis.

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