CVE-2023-20070 [Medium] | Denial of Service in Firepower Threat Defense

A vulnerability in the TLS 1.3 implementation of the Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 3 detection engine to unexpectedly restart. This vulnerability is due to a logic error in how memory allocations are handled during a TLS 1.3 session. Under specific, time-based constraints, an attacker could exploit this vulnerability by sending a crafted TLS 1.3 message sequence through an affected device. A successful exploit could allow the attacker to cause the Snort 3 detection engine to reload, resulting in a denial of service (DoS) condition. While the Snort detection engine reloads, packets going through the FTD device that are sent to the Snort detection engine will be dropped. The Snort detection engine will restart automatically. No manual intervention is required.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-02-18	0.14%	0.24%	+0.11%
2	2025-11-21	0.29%	0.14%	-0.15%
3	2025-11-18	—	0.29%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-02-18

0.14%

0.24%

+0.11%

2025-11-21

0.29%

0.14%

-0.15%

2025-11-18

—

0.29%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.0	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L` 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:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.2	1.4	[email protected]
4.0	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L` 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:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.2	1.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.0

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L 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:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.2

1.4

[email protected]

4.0

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L 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:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.2

1.4

[email protected]

Affected software / configurations for CVE-2023-20070

Vendor	Product	Version	Raw CPE
cisco	firepower_threat_defense	7.2.0	cpe:2.3:a:cisco:firepower_threat_defense:7.2.0:::::::*
cisco	firepower_threat_defense	7.2.0.1	cpe:2.3:a:cisco:firepower_threat_defense:7.2.0.1:::::::*

References for CVE-2023-20070

URL	Tags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3-uAnUntcV	Vendor Advisory

URL

CVE-2023-20070

Exploit prediction scoring system (EPSS) score for CVE-2023-20070

Common vulnerability scoring system (CVSS) metrics for CVE-2023-20070

Weakness enumeration for CVE-2023-20070

Affected software / configurations for CVE-2023-20070

References for CVE-2023-20070