Samba Printing Subsystem - Remote Code Execution

criticalseverity

9.8CVSS score

28.7%likelihood of exploitation, next 30 days

98%of all CVEs are less likely

Readycheck to confirm it

A flaw was found in the Samba printing subsystem. Samba passes the client-controlled job description string to the command configured with the "print command" setting via the "%J" substitution character without escaping shell meta characters. A remote attacker could exploit this vulnerability by sending a specially crafted print job description that contains unescaped shell characters. This could lead to remote code execution on the affected system.

Impact

Successful exploitation allows an unauthenticated remote attacker to execute arbitrary operating system commands on the Samba server, leading to full system compromise including data exfiltration, malware deployment, and lateral movement within the network.

Fix

Upgrade Samba to version 4.22.10, 4.23.8, or 4.24.3 or later, or as a workaround add single quotes directly around %J in the print command smb.conf entry or remove %J completely from the configuration.

How to confirm it

Positive when: contains "Samba" AND compare_versions(version, '< 4.22.10') || compare_versions(version, '>= 4.23.0', '< 4.23.8') || compare_versions(version, '>= 4.24.0', '< 4.24.3')

Run it with nuclei: nuclei -id CVE-2026-4480 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2026-4480

info:
  name: Samba Printing Subsystem - Remote Code Execution
  author: projectdiscovery
  severity: critical
  description: |
    A flaw was found in the Samba printing subsystem. Samba passes the client-controlled job description string to the command configured with the "print command" setting via the "%J" substitution character without escaping shell meta characters. A remote attacker could exploit this vulnerability by sending a specially crafted print job description that contains unescaped shell characters. This could lead to remote code execution on the affected system.
  impact: |
    Successful exploitation allows an unauthenticated remote attacker to execute arbitrary operating system commands on the Samba server, leading to full system compromise including data exfiltration, malware deployment, and lateral movement within the network.
  remediation: |
    Upgrade Samba to version 4.22.10, 4.23.8, or 4.24.3 or later, or as a workaround add single quotes directly around %J in the print command smb.conf entry or remove %J completely from the configuration.
  reference:
    - https://github.com/Vusal777/CVE-2026-4480-exploit-poc
    - https://www.samba.org/samba/security/CVE-2026-4480.html
    - https://nvd.nist.gov/vuln/detail/CVE-2026-4480
  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-2026-4480
    epss-score: 0.28691
    epss-percentile: 0.98156
    cwe-id: CWE-78
  metadata:
    max-request: 1
    vendor: samba
    product: samba
    shodan-query: "port:445 product:Samba"
    fofa-query: "protocol=smb && banner=Samba"
  tags: cve,cve2026,samba,rce,smb,printing,passive,vkev

javascript:
  - pre-condition: |
      isPortOpen(Host,Port);
    code: |
      let m = require("nuclei/smb");
      let c = new m.SMBClient();
      let response = c.ConnectSMBInfoMode(Host, Port);
      to_json(response);
    args:
      Host: "{{Host}}"
      Port: "445"

    matchers-condition: and
    matchers:
      - type: word
        words:
          - "Samba"

      - type: dsl
        dsl:
          - "compare_versions(version, '< 4.22.10') || compare_versions(version, '>= 4.23.0', '< 4.23.8') || compare_versions(version, '>= 4.24.0', '< 4.24.3')"

    extractors:
      - type: regex
        name: version
        group: 1
        regex:
          - "Samba ([0-9]+\\.[0-9]+\\.[0-9]+[a-z]*)"

References

Use this check only on systems you are authorised to test. Where the data comes from