CVE-2024-20321 [High] | Denial of Service in Nx-Os

A vulnerability in the External Border Gateway Protocol (eBGP) implementation of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because eBGP traffic is mapped to a shared hardware rate-limiter queue. An attacker could exploit this vulnerability by sending large amounts of network traffic with certain characteristics through an affected device. A successful exploit could allow the attacker to cause eBGP neighbor sessions to be dropped, leading to a DoS condition in the network.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.46%	0.71%	+0.25%
2	2026-03-16	0.60%	0.46%	-0.14%
3	2025-11-21	—	0.60%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.46%

0.71%

+0.25%

2026-03-16

0.60%

0.46%

-0.14%

2025-11-21

—

0.60%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.6	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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: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.	3.9	4.0	[email protected]
8.6	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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: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.	3.9	4.0	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.6

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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: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.

3.9

4.0

[email protected]

8.6

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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: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.

3.9

4.0

[email protected]

Affected software / configurations for CVE-2024-20321

Vendor	Product	Version	Raw CPE
cisco	nx-os	7.0\(3\)f1\(1\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f1\(1\):::::::*
cisco	nx-os	7.0\(3\)f2\(1\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f2\(1\):::::::*
cisco	nx-os	7.0\(3\)f2\(2\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f2\(2\):::::::*
cisco	nx-os	7.0\(3\)f3\(1\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f3\(1\):::::::*
cisco	nx-os	7.0\(3\)f3\(2\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f3\(2\):::::::*
cisco	nx-os	7.0\(3\)f3\(3\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f3\(3\):::::::*
cisco	nx-os	7.0\(3\)f3\(3a\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f3\(3a\):::::::*
cisco	nx-os	7.0\(3\)f3\(3c\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f3\(3c\):::::::*
cisco	nx-os	7.0\(3\)f3\(4\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f3\(4\):::::::*
cisco	nx-os	7.0\(3\)f3\(5\)	cpe:2.3:o:cisco:nx-os:7.0\(3\)f3\(5\):::::::*
cisco	nx-os	9.2\(1\)	cpe:2.3:o:cisco:nx-os:9.2\(1\):::::::*
cisco	nx-os	9.2\(2\)	cpe:2.3:o:cisco:nx-os:9.2\(2\):::::::*
cisco	nx-os	9.2\(2t\)	cpe:2.3:o:cisco:nx-os:9.2\(2t\):::::::*
cisco	nx-os	9.2\(2v\)	cpe:2.3:o:cisco:nx-os:9.2\(2v\):::::::*
cisco	nx-os	9.2\(3\)	cpe:2.3:o:cisco:nx-os:9.2\(3\):::::::*
cisco	nx-os	9.2\(4\)	cpe:2.3:o:cisco:nx-os:9.2\(4\):::::::*
cisco	nx-os	9.3\(1\)	cpe:2.3:o:cisco:nx-os:9.3\(1\):::::::*
cisco	nx-os	9.3\(2\)	cpe:2.3:o:cisco:nx-os:9.3\(2\):::::::*
cisco	nx-os	9.3\(3\)	cpe:2.3:o:cisco:nx-os:9.3\(3\):::::::*
cisco	nx-os	9.3\(4\)	cpe:2.3:o:cisco:nx-os:9.3\(4\):::::::*
cisco	nx-os	9.3\(5\)	cpe:2.3:o:cisco:nx-os:9.3\(5\):::::::*
cisco	nx-os	9.3\(6\)	cpe:2.3:o:cisco:nx-os:9.3\(6\):::::::*
cisco	nx-os	9.3\(7\)	cpe:2.3:o:cisco:nx-os:9.3\(7\):::::::*
cisco	nx-os	9.3\(7a\)	cpe:2.3:o:cisco:nx-os:9.3\(7a\):::::::*
cisco	nx-os	9.3\(8\)	cpe:2.3:o:cisco:nx-os:9.3\(8\):::::::*
cisco	nx-os	9.3\(9\)	cpe:2.3:o:cisco:nx-os:9.3\(9\):::::::*
cisco	nx-os	9.3\(10\)	cpe:2.3:o:cisco:nx-os:9.3\(10\):::::::*
cisco	nx-os	9.3\(11\)	cpe:2.3:o:cisco:nx-os:9.3\(11\):::::::*
cisco	nx-os	9.3\(12\)	cpe:2.3:o:cisco:nx-os:9.3\(12\):::::::*
cisco	nx-os	10.1\(1\)	cpe:2.3:o:cisco:nx-os:10.1\(1\):::::::*
cisco	nx-os	10.1\(2\)	cpe:2.3:o:cisco:nx-os:10.1\(2\):::::::*
cisco	nx-os	10.1\(2t\)	cpe:2.3:o:cisco:nx-os:10.1\(2t\):::::::*
cisco	nx-os	10.2\(1\)	cpe:2.3:o:cisco:nx-os:10.2\(1\):::::::*
cisco	nx-os	10.2\(1q\)	cpe:2.3:o:cisco:nx-os:10.2\(1q\):::::::*
cisco	nx-os	10.2\(2\)	cpe:2.3:o:cisco:nx-os:10.2\(2\):::::::*
cisco	nx-os	10.2\(3\)	cpe:2.3:o:cisco:nx-os:10.2\(3\):::::::*
cisco	nx-os	10.2\(3t\)	cpe:2.3:o:cisco:nx-os:10.2\(3t\):::::::*
cisco	nx-os	10.2\(3v\)	cpe:2.3:o:cisco:nx-os:10.2\(3v\):::::::*
cisco	nx-os	10.2\(4\)	cpe:2.3:o:cisco:nx-os:10.2\(4\):::::::*
cisco	nx-os	10.2\(5\)	cpe:2.3:o:cisco:nx-os:10.2\(5\):::::::*
cisco	nx-os	10.2\(6\)	cpe:2.3:o:cisco:nx-os:10.2\(6\):::::::*
cisco	nx-os	10.3\(1\)	cpe:2.3:o:cisco:nx-os:10.3\(1\):::::::*
cisco	nx-os	10.3\(2\)	cpe:2.3:o:cisco:nx-os:10.3\(2\):::::::*
cisco	nx-os	10.3\(3\)	cpe:2.3:o:cisco:nx-os:10.3\(3\):::::::*
cisco	nx-os	10.3\(4a\)	cpe:2.3:o:cisco:nx-os:10.3\(4a\):::::::*
cisco	nx-os	10.3\(99w\)	cpe:2.3:o:cisco:nx-os:10.3\(99w\):::::::*
cisco	nx-os	10.3\(99x\)	cpe:2.3:o:cisco:nx-os:10.3\(99x\):::::::*
cisco	nx-os	10.4\(1\)	cpe:2.3:o:cisco:nx-os:10.4\(1\):::::::*

References for CVE-2024-20321

URL	Tags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-ebgp-dos-L3QCwVJ	Vendor Advisory

URL

CVE-2024-20321

Exploit prediction scoring system (EPSS) score for CVE-2024-20321

Common vulnerability scoring system (CVSS) metrics for CVE-2024-20321

Weakness enumeration for CVE-2024-20321

Affected software / configurations for CVE-2024-20321

References for CVE-2024-20321