CVE-2023-20040 [Medium] | Denial of Service in Network Services Orchestrator

A vulnerability in the NETCONF service of Cisco Network Services Orchestrator (NSO) could allow an authenticated, remote attacker to cause a denial of service (DoS) on an affected system that is running as the root user. To exploit this vulnerability, the attacker must be a member of the admin group. This vulnerability exists because user-supplied input is not properly validated when NETCONF is used to upload packages to an affected device. An attacker could exploit this vulnerability by uploading a specially crafted package file. A successful exploit could allow the attacker to write crafted files to arbitrary locations on the filesystem or delete arbitrary files from the filesystem of an affected device, resulting in a DoS condition. Note: By default, during install, Cisco NSO will be set up to run as the root user unless the --run-as-user option is used.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	1.50%	1.24%	-0.26%
2	2026-02-04	2.15%	1.50%	-0.64%
3	2026-01-26	—	2.15%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

1.50%

1.24%

-0.26%

2026-02-04

2.15%

1.50%

-0.64%

2026-01-26

—

2.15%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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: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:H) Could take the service down hard or make it unusable for people who depend on it.	1.2	4.2	[email protected]
5.5	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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: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:H) Could take the service down hard or make it unusable for people who depend on it.	1.2	4.2	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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: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:H): Could take the service down hard or make it unusable for people who depend on it.

1.2

4.2

[email protected]

5.5

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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: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:H): Could take the service down hard or make it unusable for people who depend on it.

1.2

4.2

[email protected]

Affected software / configurations for CVE-2023-20040

Vendor	Product	Version	Raw CPE
cisco	network_services_orchestrator	>= 3.3, < 5.4.7	cpe:2.3:a:cisco:network_services_orchestrator::::::::
cisco	network_services_orchestrator	>= 5.5, < 5.5.6	cpe:2.3:a:cisco:network_services_orchestrator::::::::
cisco	network_services_orchestrator	>= 5.6, < 5.6.7	cpe:2.3:a:cisco:network_services_orchestrator::::::::
cisco	network_services_orchestrator	>= 5.7, < 5.7.4	cpe:2.3:a:cisco:network_services_orchestrator::::::::
cisco	network_services_orchestrator	5.8	cpe:2.3:a:cisco:network_services_orchestrator:5.8:::::::*

References for CVE-2023-20040

URL	Tags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nso-path-trvsl-zjBeMkZg	Vendor Advisory

URL

CVE-2023-20040

Exploit prediction scoring system (EPSS) score for CVE-2023-20040

Common vulnerability scoring system (CVSS) metrics for CVE-2023-20040

Weakness enumeration for CVE-2023-20040

Affected software / configurations for CVE-2023-20040

References for CVE-2023-20040