CVE-2021-40114 [Medium] | Information Disclosure in Firepower Threat Defense

Multiple Cisco products are affected by a vulnerability in the way the Snort detection engine processes ICMP traffic that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper memory resource management while the Snort detection engine is processing ICMP packets. An attacker could exploit this vulnerability by sending a series of ICMP packets through an affected device. A successful exploit could allow the attacker to exhaust resources on the affected device, causing the device to reload.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	3.42%	2.37%	-1.05%
2	2026-02-21	1.14%	3.42%	+2.28%
3	2026-02-20	—	1.14%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

3.42%

2.37%

-1.05%

2026-02-21

1.14%

3.42%

+2.28%

2026-02-20

—

1.14%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
6.8	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.2	4.0	[email protected]
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	3.6	[email protected]
7.8	2.0	HIGH	`AV:N/AC:L/Au:N/C:N/I:N/A:C` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:C) Complete availability impact.	10.0	6.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

6.8

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.2

4.0

[email protected]

7.5

3.1

HIGH

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

3.6

[email protected]

7.8

2.0

HIGH

AV:N/AC:L/Au:N/C:N/I:N/A:C Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:C): Complete availability impact.

10.0

6.9

[email protected]

OS Trackers for CVE-2021-40114

vendor	priority	summary	link
`alpine`	high	CVE-2021-40114: 1 source package rows (snort); 7 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 0.	https://security.alpinelinux.org/vuln/CVE-2021-40114
`ubuntu`	medium	CVE-2021-40114 medium priority: Ubuntu including 1 source packages (snort), 14 status rows across 14 suites (bionic, focal, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needed 5, ignored 4, DNE 3, not-affected 1, released 1.	https://ubuntu.com/security/CVE-2021-40114

Affected software / configurations for CVE-2021-40114

Vendor	Product	Version	Raw CPE
cisco	firepower_threat_defense	< 6.4.0.12	cpe:2.3:a:cisco:firepower_threat_defense::::::::
cisco	firepower_threat_defense	>= 6.5.0, < 6.6.3	cpe:2.3:a:cisco:firepower_threat_defense::::::::
cisco	firepower_threat_defense	>= 6.7.0, < 6.7.0.2	cpe:2.3:a:cisco:firepower_threat_defense::::::::
cisco	secure_firewall_management_center	2.9.14.0	cpe:2.3:a:cisco:secure_firewall_management_center:2.9.14.0:::::::*
cisco	secure_firewall_management_center	2.9.15	cpe:2.3:a:cisco:secure_firewall_management_center:2.9.15:::::::*
cisco	secure_firewall_management_center	2.9.16	cpe:2.3:a:cisco:secure_firewall_management_center:2.9.16:::::::*
cisco	secure_firewall_management_center	2.9.17	cpe:2.3:a:cisco:secure_firewall_management_center:2.9.17:::::::*
cisco	unified_threat_defense	>= 16.12, < 16.12.6	cpe:2.3:a:cisco:unified_threat_defense::::::::
cisco	unified_threat_defense	>= 17.3, < 17.3.4a	cpe:2.3:a:cisco:unified_threat_defense::::::::
cisco	unified_threat_defense	>= 17.4, < 17.4.2	cpe:2.3:a:cisco:unified_threat_defense::::::::
snort	snort	>= 2.0.0, < 2.9.18	cpe:2.3:a:snort:snort::::::::

References for CVE-2021-40114

URL	Tags
https://lists.debian.org/debian-lts-announce/2023/02/msg00011.html
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-dos-s2R7W9UU	Vendor Advisory
https://www.debian.org/security/2023/dsa-5354

URL

CVE-2021-40114 | Multiple Cisco Products Snort Memory Leak Denial of Service Vulnerability

Exploit prediction scoring system (EPSS) score for CVE-2021-40114

Common vulnerability scoring system (CVSS) metrics for CVE-2021-40114

Weakness enumeration for CVE-2021-40114

OS Trackers for CVE-2021-40114

Affected software / configurations for CVE-2021-40114

References for CVE-2021-40114