CVE-2026-20023 [Medium] | Out-of-bounds Write in Firepower Threat Defense …

A vulnerability in the OSPF protocol of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, adjacent attacker to corrupt memory on an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to memory corruption when parsing OSPF protocol packets. An attacker could exploit this vulnerability by sending crafted OSPF packets to an affected device. A successful exploit could allow the attacker to cause memory corruption causing the affected device to reboot, resulting in a DoS condition.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.02%	0.15%	+0.13%
2	2026-03-05	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.02%

0.15%

+0.13%

2026-03-05

—

0.02%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
6.1	3.1	MEDIUM	`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. 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.	1.6	4.0	[email protected]
6.5	3.1	MEDIUM	`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. 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.	2.8	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

6.1

3.1

MEDIUM

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

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
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.

1.6

4.0

[email protected]

6.5

3.1

MEDIUM

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

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
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.

2.8

3.6

[email protected]

Affected software / configurations for CVE-2026-20023

References for CVE-2026-20023

URL	Tags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ospf-ZH8PhbSW	Vendor Advisory

URL

CVE-2026-20023

Exploit prediction scoring system (EPSS) score for CVE-2026-20023

Common vulnerability scoring system (CVSS) metrics for CVE-2026-20023

Weakness enumeration for CVE-2026-20023

Affected software / configurations for CVE-2026-20023

References for CVE-2026-20023

Vendor	Product	Version	Raw CPE
cisco	firepower_threat_defense_software	6.4.0	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0:::::::*
cisco	firepower_threat_defense_software	6.4.0.1	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.1:::::::*
cisco	firepower_threat_defense_software	6.4.0.2	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.2:::::::*
cisco	firepower_threat_defense_software	6.4.0.3	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.3:::::::*
cisco	firepower_threat_defense_software	6.4.0.4	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.4:::::::*
cisco	firepower_threat_defense_software	6.4.0.5	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.5:::::::*
cisco	firepower_threat_defense_software	6.4.0.6	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.6:::::::*
cisco	firepower_threat_defense_software	6.4.0.7	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.7:::::::*
cisco	firepower_threat_defense_software	6.4.0.8	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.8:::::::*
cisco	firepower_threat_defense_software	6.4.0.9	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.9:::::::*
cisco	firepower_threat_defense_software	6.4.0.10	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.10:::::::*
cisco	firepower_threat_defense_software	6.4.0.11	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.11:::::::*
cisco	firepower_threat_defense_software	6.4.0.12	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.12:::::::*
cisco	firepower_threat_defense_software	6.4.0.13	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.13:::::::*
cisco	firepower_threat_defense_software	6.4.0.14	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.14:::::::*
cisco	firepower_threat_defense_software	6.4.0.15	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.15:::::::*
cisco	firepower_threat_defense_software	6.4.0.16	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.16:::::::*
cisco	firepower_threat_defense_software	6.4.0.17	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.17:::::::*
cisco	firepower_threat_defense_software	6.4.0.18	cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0.18:::::::*
cisco	firepower_threat_defense_software	7.0.0	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.0:::::::*
cisco	firepower_threat_defense_software	7.0.0.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.0.1:::::::*
cisco	firepower_threat_defense_software	7.0.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.1:::::::*
cisco	firepower_threat_defense_software	7.0.1.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.1.1:::::::*
cisco	firepower_threat_defense_software	7.0.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.2:::::::*
cisco	firepower_threat_defense_software	7.0.2.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.2.1:::::::*
cisco	firepower_threat_defense_software	7.0.3	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.3:::::::*
cisco	firepower_threat_defense_software	7.0.4	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.4:::::::*
cisco	firepower_threat_defense_software	7.0.5	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.5:::::::*
cisco	firepower_threat_defense_software	7.0.6	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.6:::::::*
cisco	firepower_threat_defense_software	7.0.6.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.6.1:::::::*
cisco	firepower_threat_defense_software	7.0.6.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.6.2:::::::*
cisco	firepower_threat_defense_software	7.0.6.3	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.6.3:::::::*
cisco	firepower_threat_defense_software	7.0.7	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.7:::::::*
cisco	firepower_threat_defense_software	7.0.8	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.8:::::::*
cisco	firepower_threat_defense_software	7.0.8.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.0.8.1:::::::*
cisco	firepower_threat_defense_software	7.1.0	cpe:2.3:a:cisco:firepower_threat_defense_software:7.1.0:::::::*
cisco	firepower_threat_defense_software	7.1.0.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.1.0.1:::::::*
cisco	firepower_threat_defense_software	7.1.0.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.1.0.2:::::::*
cisco	firepower_threat_defense_software	7.1.0.3	cpe:2.3:a:cisco:firepower_threat_defense_software:7.1.0.3:::::::*
cisco	firepower_threat_defense_software	7.2.0	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.0:::::::*
cisco	firepower_threat_defense_software	7.2.0.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.0.1:::::::*
cisco	firepower_threat_defense_software	7.2.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.1:::::::*
cisco	firepower_threat_defense_software	7.2.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.2:::::::*
cisco	firepower_threat_defense_software	7.2.3	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.3:::::::*
cisco	firepower_threat_defense_software	7.2.4	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.4:::::::*
cisco	firepower_threat_defense_software	7.2.4.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.4.1:::::::*
cisco	firepower_threat_defense_software	7.2.5	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.5:::::::*
cisco	firepower_threat_defense_software	7.2.5.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.5.1:::::::*
cisco	firepower_threat_defense_software	7.2.5.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.5.2:::::::*
cisco	firepower_threat_defense_software	7.2.6	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.6:::::::*
cisco	firepower_threat_defense_software	7.2.7	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.7:::::::*
cisco	firepower_threat_defense_software	7.2.8	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.8:::::::*
cisco	firepower_threat_defense_software	7.2.8.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.8.1:::::::*
cisco	firepower_threat_defense_software	7.2.9	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.9:::::::*
cisco	firepower_threat_defense_software	7.2.10	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.10:::::::*
cisco	firepower_threat_defense_software	7.2.10.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.2.10.2:::::::*
cisco	firepower_threat_defense_software	7.3.0	cpe:2.3:a:cisco:firepower_threat_defense_software:7.3.0:::::::*
cisco	firepower_threat_defense_software	7.3.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.3.1:::::::*
cisco	firepower_threat_defense_software	7.3.1.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.3.1.1:::::::*
cisco	firepower_threat_defense_software	7.3.1.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.3.1.2:::::::*
cisco	firepower_threat_defense_software	7.4.0	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.0:::::::*
cisco	firepower_threat_defense_software	7.4.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.1:::::::*
cisco	firepower_threat_defense_software	7.4.1.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.1.1:::::::*
cisco	firepower_threat_defense_software	7.4.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.2:::::::*
cisco	firepower_threat_defense_software	7.4.2.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.2.1:::::::*
cisco	firepower_threat_defense_software	7.4.2.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.2.2:::::::*
cisco	firepower_threat_defense_software	7.4.2.3	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.2.3:::::::*
cisco	firepower_threat_defense_software	7.4.2.4	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.2.4:::::::*
cisco	firepower_threat_defense_software	7.4.3	cpe:2.3:a:cisco:firepower_threat_defense_software:7.4.3:::::::*
cisco	firepower_threat_defense_software	7.6.0	cpe:2.3:a:cisco:firepower_threat_defense_software:7.6.0:::::::*
cisco	firepower_threat_defense_software	7.6.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.6.1:::::::*
cisco	firepower_threat_defense_software	7.6.2	cpe:2.3:a:cisco:firepower_threat_defense_software:7.6.2:::::::*
cisco	firepower_threat_defense_software	7.6.2.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.6.2.1:::::::*
cisco	firepower_threat_defense_software	7.7.0	cpe:2.3:a:cisco:firepower_threat_defense_software:7.7.0:::::::*
cisco	firepower_threat_defense_software	7.7.10.1	cpe:2.3:a:cisco:firepower_threat_defense_software:7.7.10.1:::::::*
cisco	adaptive_security_appliance_software	9.12.1	cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.1:::::::*
cisco	adaptive_security_appliance_software	9.12.1.2	cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.1.2:::::::*
cisco	adaptive_security_appliance_software	9.12.1.3	cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.1.3:::::::*
cisco	adaptive_security_appliance_software	9.12.2	cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.2:::::::*
cisco	adaptive_security_appliance_software	9.12.2.1	cpe:2.3:o:cisco:adaptive_security_appliance_software:9.12.2.1:::::::*