CVE-2025-20124 [Critical] | Security Vulnerability in Identity Services Engine

A vulnerability in an API of Cisco ISE could allow an authenticated, remote attacker to execute arbitrary commands as the root user on an affected device. This vulnerability is due to insecure deserialization of user-supplied Java byte streams by the affected software. An attacker could exploit this vulnerability by sending a crafted serialized Java object to an affected API. A successful exploit could allow the attacker to execute arbitrary commands on the device and elevate privileges. Note: To successfully exploit this vulnerability, the attacker must have valid read-only administrative credentials. In a single-node deployment, new devices will not be able to authenticate during the reload time.

EDB-ID	Source	Kind	Published	Link
52396	exploit_db	edb	2025-08-11	Exploit-DB ↗

EDB-ID

Source

Kind

Published

Link

52396

exploit_db

edb

2025-08-11

Exploit-DB ↗

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-21	8.30%	9.51%	+1.21%
2	2026-03-16	0.87%	8.30%	+7.43%
3	2026-03-03	—	0.87%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-21

8.30%

9.51%

+1.21%

2026-03-16

0.87%

8.30%

+7.43%

2026-03-03

—

0.87%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.9	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/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:L) A normal user session is enough; they don’t have to be admin. 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:L) Some sensitive info could get out, but not a total data dump. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.1	6.0	[email protected]
7.2	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/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:H) They need powerful rights—admin, root, or similar—before this pays off. 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:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.2	5.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.9

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/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:L): A normal user session is enough; they don’t have to be admin.
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:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.1

6.0

[email protected]

7.2

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/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:H): They need powerful rights—admin, root, or similar—before this pays off.
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:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.2

5.9

[email protected]

Affected software / configurations for CVE-2025-20124

Vendor	Product	Version	Raw CPE
cisco	identity_services_engine	< 3.1	cpe:2.3:a:cisco:identity_services_engine::::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:-::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch1::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch2::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch3::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch4::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch5::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch6::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch7::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch8::::::
cisco	identity_services_engine	3.1.0	cpe:2.3:a:cisco:identity_services_engine:3.1.0:patch9::::::
cisco	identity_services_engine	3.2.0	cpe:2.3:a:cisco:identity_services_engine:3.2.0:-::::::
cisco	identity_services_engine	3.2.0	cpe:2.3:a:cisco:identity_services_engine:3.2.0:patch1::::::
cisco	identity_services_engine	3.2.0	cpe:2.3:a:cisco:identity_services_engine:3.2.0:patch2::::::
cisco	identity_services_engine	3.2.0	cpe:2.3:a:cisco:identity_services_engine:3.2.0:patch3::::::
cisco	identity_services_engine	3.2.0	cpe:2.3:a:cisco:identity_services_engine:3.2.0:patch4::::::
cisco	identity_services_engine	3.2.0	cpe:2.3:a:cisco:identity_services_engine:3.2.0:patch5::::::
cisco	identity_services_engine	3.2.0	cpe:2.3:a:cisco:identity_services_engine:3.2.0:patch6::::::
cisco	identity_services_engine	3.3.0	cpe:2.3:a:cisco:identity_services_engine:3.3.0:-::::::
cisco	identity_services_engine	3.3.0	cpe:2.3:a:cisco:identity_services_engine:3.3.0:patch1::::::
cisco	identity_services_engine	3.3.0	cpe:2.3:a:cisco:identity_services_engine:3.3.0:patch2::::::
cisco	identity_services_engine	3.3.0	cpe:2.3:a:cisco:identity_services_engine:3.3.0:patch3::::::

References for CVE-2025-20124

URL	Tags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-multivuls-FTW9AOXF	Vendor Advisory

URL

CVE-2025-20124 | Cisco Identity Services Engine Java Deserialization Vulnerability

Public exploit references (Exploit-DB) for CVE-2025-20124

Exploit prediction scoring system (EPSS) score for CVE-2025-20124

Common vulnerability scoring system (CVSS) metrics for CVE-2025-20124

Weakness enumeration for CVE-2025-20124

Affected software / configurations for CVE-2025-20124

References for CVE-2025-20124