CVE-2026-24423: SmarterTools SmarterMail 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

SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution vulnerability in the ConnectToHub API method. The attacker could point the SmarterMail to the malicious HTTP server, which serves the malicious OS command. This command will be executed by the vulnerable application.

Description quoted from the CVE record (assigned by VulnCheck, published 2026-01-23).

Weakness: CWE-306 Missing Authentication for Critical Function

How it can be exploited

Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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

On CISA KEV since: 2026-02-05
US federal deadline: 2026-02-26
Ransomware use: Yes

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-01226, CNNVD-202601-3955, EUVD-2026-4273, GHSA-7jpw-fm5p-f98m

VEDAS cluster: VEDAS:FLUTTERSHADE

Exploit Observer links 9 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (9)

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

Nuclei template: https://raw.githubusercontent.com/projectdiscovery/nuclei-templates/main/http/cves/2026/CVE-2026-24423.yaml
Code repository: https://github.com/aavamin/cve-2026-24423
Code repository: https://github.com/cyberalp0/smartermail-cve-2026-24423
Code repository: https://github.com/cyberalp0/smartermail-cve-2026-24423-
Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/nuclei/2026/CVE-2026-24423.yaml
Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/nuclei/2026/CVE-2026-24423.yaml
Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-24423.rules
Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-24423.rules
Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-24423.rules

Vulnerability databases and vendor advisories (6)

Catalogue entries, not exploit evidence.

Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-4273
Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-7jpw-fm5p-f98m
Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-24423
Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24423
Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202601-3955
Vulnerability database or vendor advisory: https://www.tenable.com/cve/CVE-2026-24423

25 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: 0.882
very likely to be attacked soon
VEDAS: 0.986
strong exploit evidence
On CISA KEV: Yes, since 2026-02-05
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
SmarterTools SmarterMail	before 100.0.9511	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: smartertools smartermail, smartertools_inc. smartermail.

How to fix it

Fixed versions stated in the CVE record: 100.0.9511.

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:

https://www.smartertools.com/smartermail/release-notes/current (release-notes, patch)

How to detect it

Nuclei template (active check)

Smartermail - Missing Authentication
SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution vulnerability in the ConnectToHub API method. The attacker could point the SmarterMail to the malicious HTTP server, which serves the malicious OS command.

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

The template sends 1 request (POST /api/v1/settings/sysadmin/connect-to-hub); it confirms through an out-of-band callback (interactsh), so the scanner must be able to receive it; it decides using 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-2026-24423.yaml

Show the template (41 lines)

yaml

id: CVE-2026-24423

info:
  name: "Smartermail - Missing Authentication"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution
    vulnerability in the ConnectToHub API method. The attacker could point the SmarterMail to the malicious HTTP
    server, which serves the malicious OS command.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-24423&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=smartermail&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-2026-24423
    cwe-id: CWE-306
  metadata:
    verified: false
  tags: cve,cve2026,smartermail,rce,oast,kev,vkev
http:
  - raw:
      - |
        POST /api/v1/settings/sysadmin/connect-to-hub HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/json

        {"hubAddress":"http://{{interactsh-url}}","oneTimePassword":"{{randstr}}","nodeName":"{{randstr}}"}

    matchers-condition: and
    matchers:
      - type: word
        part: interactsh_protocol
        words:
          - "http"

      - type: word
        part: interactsh_request
        words:
          - "setup-initial-connection"

CVE-2026-24423.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-24423 Smartermail - Missing Authentication. 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-2026-24423 Smartermail - Missing Authentication"; flow:established,to_server; http.uri; content:"connect-to-hub"; nocase; http.request_body; content:"http://"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2026-24423; reference:url,https://www.exploit.observer/?keyword=CVE-2026-24423&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=smartermail&match=exact; sid:1010228; rev:1;)

CVE-2026-24423.rules on GitHub

References

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.