CVE-2025-20144 [Medium] | Security Bypass in Ios Xr

A vulnerability in the hybrid access control list (ACL) processing of IPv4 packets in Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass a configured ACL. This vulnerability is due to incorrect handling of packets when a specific configuration of the hybrid ACL exists. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to bypass a configured ACL on the affected device. For more information, see the section of this advisory. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-20	0.06%	0.04%	-0.01%
2	2025-10-28	0.04%	0.06%	+0.01%
3	2025-10-27	—	0.04%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-20

0.06%

0.04%

-0.01%

2025-10-28

0.04%

0.06%

+0.01%

2025-10-27

—

0.04%

—

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:L/A:N` 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:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.2	1.4	[email protected]
5.8	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N` 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: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:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	3.9	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:L/A:N 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:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

2.2

1.4

[email protected]

5.8

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N 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: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:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

3.9

1.4

[email protected]

Affected software / configurations for CVE-2025-20144

Vendor	Product	Version	Raw CPE
cisco	ios_xr	6.5.1	cpe:2.3:o:cisco:ios_xr:6.5.1:::::::*
cisco	ios_xr	6.5.2	cpe:2.3:o:cisco:ios_xr:6.5.2:::::::*
cisco	ios_xr	6.5.3	cpe:2.3:o:cisco:ios_xr:6.5.3:::::::*
cisco	ios_xr	6.5.92	cpe:2.3:o:cisco:ios_xr:6.5.92:::::::*
cisco	ios_xr	6.5.93	cpe:2.3:o:cisco:ios_xr:6.5.93:::::::*
cisco	ios_xr	6.6.1	cpe:2.3:o:cisco:ios_xr:6.6.1:::::::*
cisco	ios_xr	6.6.2	cpe:2.3:o:cisco:ios_xr:6.6.2:::::::*
cisco	ios_xr	6.6.3	cpe:2.3:o:cisco:ios_xr:6.6.3:::::::*
cisco	ios_xr	6.6.4	cpe:2.3:o:cisco:ios_xr:6.6.4:::::::*
cisco	ios_xr	6.6.25	cpe:2.3:o:cisco:ios_xr:6.6.25:::::::*
cisco	ios_xr	7.0.1	cpe:2.3:o:cisco:ios_xr:7.0.1:::::::*
cisco	ios_xr	7.0.2	cpe:2.3:o:cisco:ios_xr:7.0.2:::::::*
cisco	ios_xr	7.0.90	cpe:2.3:o:cisco:ios_xr:7.0.90:::::::*
cisco	ios_xr	7.1.1	cpe:2.3:o:cisco:ios_xr:7.1.1:::::::*
cisco	ios_xr	7.1.2	cpe:2.3:o:cisco:ios_xr:7.1.2:::::::*
cisco	ios_xr	7.2.1	cpe:2.3:o:cisco:ios_xr:7.2.1:::::::*
cisco	ios_xr	7.2.2	cpe:2.3:o:cisco:ios_xr:7.2.2:::::::*
cisco	ios_xr	7.3.1	cpe:2.3:o:cisco:ios_xr:7.3.1:::::::*
cisco	ios_xr	7.3.2	cpe:2.3:o:cisco:ios_xr:7.3.2:::::::*
cisco	ios_xr	7.3.3	cpe:2.3:o:cisco:ios_xr:7.3.3:::::::*
cisco	ios_xr	7.3.4	cpe:2.3:o:cisco:ios_xr:7.3.4:::::::*
cisco	ios_xr	7.3.5	cpe:2.3:o:cisco:ios_xr:7.3.5:::::::*
cisco	ios_xr	7.3.6	cpe:2.3:o:cisco:ios_xr:7.3.6:::::::*
cisco	ios_xr	7.4.1	cpe:2.3:o:cisco:ios_xr:7.4.1:::::::*
cisco	ios_xr	7.4.2	cpe:2.3:o:cisco:ios_xr:7.4.2:::::::*
cisco	ios_xr	7.5.1	cpe:2.3:o:cisco:ios_xr:7.5.1:::::::*
cisco	ios_xr	7.5.2	cpe:2.3:o:cisco:ios_xr:7.5.2:::::::*
cisco	ios_xr	7.5.3	cpe:2.3:o:cisco:ios_xr:7.5.3:::::::*
cisco	ios_xr	7.5.4	cpe:2.3:o:cisco:ios_xr:7.5.4:::::::*
cisco	ios_xr	7.5.5	cpe:2.3:o:cisco:ios_xr:7.5.5:::::::*
cisco	ios_xr	7.6.1	cpe:2.3:o:cisco:ios_xr:7.6.1:::::::*
cisco	ios_xr	7.6.2	cpe:2.3:o:cisco:ios_xr:7.6.2:::::::*
cisco	ios_xr	7.7.1	cpe:2.3:o:cisco:ios_xr:7.7.1:::::::*
cisco	ios_xr	7.7.2	cpe:2.3:o:cisco:ios_xr:7.7.2:::::::*
cisco	ios_xr	7.7.21	cpe:2.3:o:cisco:ios_xr:7.7.21:::::::*
cisco	ios_xr	7.8.1	cpe:2.3:o:cisco:ios_xr:7.8.1:::::::*
cisco	ios_xr	7.8.2	cpe:2.3:o:cisco:ios_xr:7.8.2:::::::*
cisco	ios_xr	7.8.22	cpe:2.3:o:cisco:ios_xr:7.8.22:::::::*
cisco	ios_xr	7.9.1	cpe:2.3:o:cisco:ios_xr:7.9.1:::::::*
cisco	ios_xr	7.9.2	cpe:2.3:o:cisco:ios_xr:7.9.2:::::::*
cisco	ios_xr	7.10.1	cpe:2.3:o:cisco:ios_xr:7.10.1:::::::*
cisco	ios_xr	7.10.2	cpe:2.3:o:cisco:ios_xr:7.10.2:::::::*
cisco	ios_xr	7.11.1	cpe:2.3:o:cisco:ios_xr:7.11.1:::::::*

References for CVE-2025-20144

URL	Tags
https://blog.apnic.net/2024/09/02/crafting-endless-as-paths-in-bgp/	Technical Description
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ncs-hybridacl-crMZFfKQ	Vendor Advisory

URL

CVE-2025-20144 | Cisco IOS XR Software Access Control List Bypass Vulnerability

Exploit prediction scoring system (EPSS) score for CVE-2025-20144

Common vulnerability scoring system (CVSS) metrics for CVE-2025-20144

Weakness enumeration for CVE-2025-20144

Affected software / configurations for CVE-2025-20144

References for CVE-2025-20144