Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Software-Based SSL/TLS Denial of Service Vulnerability (Cisco Cisco Adaptive Security Appliance (ASA) Software)

CVE-2021-34783

HIGH 8.6

At a glance

Source: NVD
EPSS: EPSS 1.61 % · percentile 76 (2026-10-30)
State: PUBLISHED
Published: 2021-10-27 18:55 UTC
Updated: 2024-11-07 21:46 UTC
Assigner: cisco
NVD status: Modified

Search on…

Description

A vulnerability in the software-based SSL/TLS message handler of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to insufficient validation of SSL/TLS messages when the device performs software-based SSL/TLS decryption. An attacker could exploit this vulnerability by sending a crafted SSL/TLS message to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Note: Datagram TLS (DTLS) messages cannot be used to exploit this vulnerability.

Weaknesses (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-20 — Improper Input Validation

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-tls-decrypt-dos-BMxYjm8M

Scores

Version	Score	Vector	Scored by
CVSS 3.1	HIGH 8.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H	cisco
CVSS 3.1	HIGH 8.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H	NVD · psirt@cisco.com (Secondary)
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	NVD · nvd@nist.gov (Primary)
CVSS 2.0	HIGH 7.8	AV:N/AC:L/Au:N/C:N/I:N/A:C	NVD · nvd@nist.gov (Primary)

European references

ENISA EUVD · EUVD-2021-21433
GCVE · GCVE-0-2021-34783

CERT-FR advisories

CERTFR-2021-AVI-829 — Multiples vulnérabilités dans les produits Cisco · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* ≥ 6.4.0 < 6.4.0.13
cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* ≥ 6.6.0 < 6.6.5
cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* ≥ 6.7.0 < 6.7.0.3
cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* ≥ 7.0.0 < 7.0.1
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* ≥ 9.8.0 < 9.8.4.40
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* ≥ 9.12.0 < 9.12.4.29
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* ≥ 9.14.0 < 9.14.3.9
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* ≥ 9.15.0 < 9.15.1.17
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* ≥ 9.16.0 < 9.16.2
cpe:2.3:o:cisco:asa_5512-x_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5512-x_firmware:009.016\(001.025\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5505_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5505_firmware:009.016\(001.025\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5515-x_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5515-x_firmware:009.016\(001.025\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5525-x_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5525-x_firmware:009.016\(001.025\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5545-x_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5545-x_firmware:009.016\(001.025\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5555-x_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5555-x_firmware:009.016\(001.025\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5580_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5580_firmware:009.016\(001.025\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5585-x_firmware:009.016\(001\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:asa_5585-x_firmware:009.016\(001.025\):*:*:*:*:*:*:*

Affected products

Product	Versions
Cisco · Cisco Adaptive Security Appliance (ASA) Software	affected n/a

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD

⚠️ Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Software-Based SSL/TLS Denial of Service Vulnerability (Cisco Cisco Adaptive Security Appliance (ASA) Software)