CVE-2026-23760 SmarterTools SmarterMail Authentication Bypass Using an Alternate Path or Channel Vulnerability
BLUF
CVE-2026-23760 is a critical (CVSS 9.3) authentication bypass vulnerability in SmarterTools SmarterMail. It allows unauthenticated remote attackers to reset the password of any user, including system administrators, by making anonymous requests to the force-reset-password API endpoint.
Executive Cost Summary
This cost analysis was developed by the CyberDax team using expert judgment and assisted analytical tools to support clarity and consistency.
For organizations affected by exploitation of CVE-2026-23760 enabling unauthorized administrative access to enterprise email infrastructure:
· Low-end total cost: $150,000 – $350,000
o (rapid detection, limited dwell time, no data exfiltration)
· Typical expected range: $450,000 – $1.2 million
o (admin compromise confirmed, email integrity impacted, contained escalation)
· Upper-bound realistic scenarios: $2.0 – $4.5 million
o (extended persistence, downstream fraud risk, regulatory exposure)
Key Cost Drivers
· Time-to-detection and attacker dwell time within mail infrastructure
· Scope of privileged account resets and mailbox access
· Business reliance on SmarterMail for core communications
· Regulatory environment governing email-stored data
· Need for full credential resets and trust re-establishment
Potential Affected Sectors
Any organization utilizing SmarterMail for enterprise email, typically affecting Small and Medium-Sized Businesses (SMBs) and large enterprises.
Potential Impacted Countries
· Global distribution
Date of First Reported Activity
· January 15, 2026
Date of Last Reported Activity
· January 26, 2026
Tools Used in Campaign
· Custom exploit scripts targeting the force-reset-password endpoint.
TTPs
· T1190 Exploit Public-Facing Application
o Adversaries target the vulnerable SmarterMail web application's password reset API endpoint.
· T1078 Valid Accounts
o By resetting the administrator password, attackers gain access to legitimate, highly privileged accounts.
· T1059 Command and Scripting Interpreter
o Attackers use the hijacked administrative access to execute operating system commands via SmarterMail's built-in management functionality.
· T1053 Scheduled Task/Job (System Events)
o Threat actors have been observed creating malicious "System Events" within SmarterMail to trigger reconnaissance or other commands automatically (e.g., when a new domain is added).
· T1087.002 Account Discovery Domain Account
o Attackers utilize the administrative compromise to identify and target specific users or domains within the SmarterMail instance.
· T1070 Indicator Removal
o Post-exploitation activity includes deleting malicious system events or logs to hide traces of the intrusion.
CVE-2026-23760
CVSS 3.1
· (9.8) AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS:4.0
· (9.3) /AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H (Score: 9.3).
Nessus ID
· CVE-2026-23760 does not have a plug in at this time
Is CVE-2026-23760 on the KEV List?
· Yes
CISA Patch by Date
· February 16, 2026
Patching/Mitigation Data
Patch Release Date
· January 15, 2026
Patch Link
· hxxps://www.vulncheck.com/advisories/smartertools-smartermail-authentication-bypass-via-password-reset-apiMalware Context:
Malware Names
· There has been no malware associated with CVE-2026-23760 at this time.
Malware Family
· There has been no malware associated with CVE-2026-23760 at this time.
SHA256
· There has been no malware associated with CVE-2026-23760 at this time.
o Activity relies on direct API exploitation; file-based payloads are typically delivered after administrative access is achieved.
Primary Objectives
· Administrative compromise of the email server to perform further Remote Code Execution (RCE) on the underlying host or data exfiltration.
Suggested Rules / Potential Hunts
As a reminder, these are indicator rules. They are likely to be noisy.
For best results consider creating a data model and reviewing the traffic as a report.
Suricata
Suggested Rule:
alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET EXPLOIT SmarterMail force-reset-password Auth Bypass (CVE-2026-23760)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/force-reset-password"; fast_pattern; http.content_type; content:"application/json"; classtype:attempted-admin; sid:20260101; rev:1; metadata:cve 2026_23760;)
SentinelOne
· Process Execution from Web Service
o Search for SmarterMail spawning suspicious child processes.
ObjectType = "Process" AND ParentProcessName = "MailService.exe" AND ProcessName IN ("cmd.exe", "powershell.exe", "wscript.exe", "cscript.exe")
· File Creation in Persistence Locations
o Look for new files dropped in startup folders or web directories.
ObjectType = "File" AND ProcessName = "MailService.exe" AND (FilePath CONTAINS "Startup" OR FilePath CONTAINS "App_Data")
API Endpoint Access Logs: If S1 is ingesting application logs:
EndpointPath = "/force-reset-password"
Splunk
Detect External Password Resets:
splunk
index=web sourcetype=iis cs_method=POST cs_uri_stem="*force-reset-password*"
| stats count by src_ip, cs_uri_stem, sc_status, dest
· Look for admin logins from new or unusual IP addresses immediately following a password reset event.
index=smartermail_logs "force-reset-password"
| transaction src_ip maxspan=5m
| table _time, src_ip, user, action
Delivery Methods
· Direct network-based API exploitation (pre-auth).
Reference
NVD
· hxxps://nvd.nist.gov/vuln/detail/CVE-2026-23760
CISA KEV Catalog
· hxxps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=cve-2026-23760
Tenable
· hxxps://www.tenable.com/cve/CVE-2026-23760/plugins
VulnCheck
· hxxps://www.vulncheck.com/advisories/smartertools-smartermail-authentication-bypass-via-password-reset-api
