Denial of service in multiple Cisco Products

Published: 2021-10-29
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-40114
Exploitation vector Network
Public exploit N/A
Vulnerable software
Server applications / IDS/IPS systems, Firewalls and proxy servers

Cisco Firepower Threat Defense (FTD)
Hardware solutions / Security hardware applicances

Cisco UTD Snort IPS Engine Software for IOS XE
Other software / Other software solutions

Cisco UTD Engine for IOS XE SD-WAN
Other software / Other software solutions

Vendor Sourcefire
Cisco Systems, Inc

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Memory leak

EUVDB-ID: #VU57799

Risk: Medium

CVSSv3.1: 5.9 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-40114

CWE-ID: CWE-401 - Improper Release of Memory Before Removing Last Reference ('Memory Leak')

Exploit availability: No


The vulnerability allows a remote attacker to perform DoS attack on the target system.

The vulnerability exists due memory leak while the Snort detection engine is processing ICMP packets. A remote attacker can send a specially crafted ICMP packet, force the application to leak memory and perform denial of service attack.


Install update from vendor's website.

Vulnerable software versions

Snort: 2.1.0 -

Cisco Firepower Threat Defense (FTD): 6.2.2 - 6.7.0

Cisco UTD Snort IPS Engine Software for IOS XE: 16.12 - 17.4

Cisco UTD Engine for IOS XE SD-WAN: 16.12 - 17.4

CPE2.3 External links

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.