Security Digest · Vulnerability record · Known exploited
CVE-2026-24423: SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability
Exploited in the wild (CISA KEV). SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution vulnerability in the ConnectToHub API method.
CISA KEV · added 2026-02-05 CVSS 9.3 Critical EPSS 88.2% · p99.8
Should you act?
Exploited: patch now if you run it
CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Yes, if you run SmarterTools SmarterMail. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-02-05, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-02-26; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns.
- EPSS 88.2%, percentile 99.8: FIRST’s model estimates a 88.2% chance of exploitation activity in the next 30 days, higher than 99.8% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize 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.
CISA’s summary
SmarterTools SmarterMail contains a missing authentication for critical function vulnerability in the ConnectToHub API method. This could allow the attacker to point the SmarterMail instance to a malicious HTTP server which serves the malicious OS command and could lead to command execution.
Weakness type: CWE-306.
Product: SmarterTools SmarterMail · Assigned by: VulnCheck · Published: 2026-01-23
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| SmarterTools | SmarterMail | < 100.0.9511 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| VulnCheck | 4.0 | 9.3 Critical | 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 |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: none (no login)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: added 2026-02-05; federal due date 2026-02-26. Known ransomware use: Known.
- 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.
- CISA SSVC assessment: exploitation active, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 88.18% probability of exploitation activity in the next 30 days; percentile 99.8.
Timeline
- — CVE record published by VulnCheck
- — Added to CISA’s Known Exploited Vulnerabilities catalog
- — CISA remediation deadline for US federal agencies
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- smartertools.com smartertools.com
Vulnerability records
- CVE.org record CVE-2026-24423 cve.org
- NVD entry CVE-2026-24423 nvd.nist.gov
Government
Other references from the CVE record and advisory
- code-white.com code-white.com
- vulncheck.com vulncheck.com
All exploited SmarterTools vulnerabilities · Today’s Security Digest