How severe is CVE-2026-24423?

No CVSS score has been assigned to CVE-2026-24423 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-24423?

Affected package information for CVE-2026-24423 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-24423?

No fixed release is recorded for CVE-2026-24423 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2026-24423 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2026-24423 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-24423 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2026-24423, including . All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2026-24423?

CVE-2026-24423 has an EPSS (Exploit Prediction Scoring System) score of 88.2%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2026-24423 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2026-24423 (SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-02-05. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-02-26. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2026-24423?

CVE-2026-24423 is classified as Missing Authentication (CWE-306). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for CVE-2026-24423?

A Nuclei detection template exists for CVE-2026-24423, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2026-24423 published, and has it been updated?

CVE-2026-24423 was published on January 23, 2026 and was last updated on August 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV · ACTIVELY EXPLOITED

CVE-2026-24423

CVE-2026-24423 is a Missing Authentication vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-02-05) and has been used in ransomware campaigns — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

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…

Published

Jan 23, 2026

Updated

Aug 4, 2026

Affected

1 product

Patched

See advisory

Exploits

1 known

Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-02-05 — including use in ransomware campaigns. Federal agencies were required to remediate by 2026-02-26.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2026-24423.

EPSS Exploitation Probability

via FIRST.org ↗

88.2%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

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. This command will be executed by the vulnerable application.

Affected Products

1 product · 1 configurations

Application

smartermailsmartertools

< 100.0.9511

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

aavamin/CVE-2026-24423

CVE-2026-24423 exp

⭐ 8🍴 1Aug 2026

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2026-24423 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

How to detect CVE-2026-24423

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2026-24423 -u https://target

Template: SmarterMail - Remote Code Execution
Severity: critical
Impact: Remote attackers can execute arbitrary OS commands, potentially leading to full system compromise.
Remediation: Update to build 9511 or later.

Template by ProjectDiscovery nuclei-templates (jyoti369), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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