SmarterTools SmarterMail Authentication Bypass Using an Alternate Path or Channel
CVE-2026-23760 is a critical-severity authentication bypass using an alternate path or channel vulnerability in SmarterMail from SmarterTools, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 100.0.9511 as the first without the flaw, so updating SmarterMail to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on January 26, 2026, which means attacks have been observed in the wild, including in ransomware campaigns.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update SmarterMail to 100.0.9511 or a later version.
- CISA's 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.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| SmarterTools | SmarterMail | before 100.0.9511 | 100.0.9511 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (vulncheck.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
SmarterTools SmarterMail versions prior to build 9511 contain an authentication bypass vulnerability in the password reset API. The force-reset-password endpoint permits anonymous requests and fails to verify the existing password or a reset token when resetting system administrator accounts. An unauthenticated attacker can supply a target administrator username and a new password to reset the account, resulting in full administrative compromise of the SmarterMail instance. NOTE: SmarterMail system administrator privileges grant the ability to execute operating system commands via built-in management functionality, effectively providing administrative (SYSTEM or root) access on the underlying host.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass Using an Alternate Path or Channel
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
How developers prevent this class of flaw
- Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
More Authentication Bypass Using an Alternate Path or Channel vulnerabilities (CWE-288)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- smartertools.com/smartermail/release-notes/currentRelease Notes
Third-party and government advisories
- code-white.com/public-vulnerability-list/#authenticationserviceforceresetpassword-missing-authentication-in-s…Third Party Advisory
- vulncheck.com/advisories/smartertools-smartermail-authentication-bypass-via-password-reset-apiThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-23760US Government Resource
Technical write-ups (may include proof of concept)
- labs.watchtowr.com/attackers-with-decompilers-strike-again-smartertools-smartermail-wt-2026-0001-auth-bypass/Exploit, Third Party Advisory
- huntress.com/blog/smartermail-account-takeover-leading-to-rceExploit, Third Party Advisory
Other vulnerabilities in SmarterMail
- 8.8 High severity
- 7.2 High severity
- 8.8 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 10.0 Critical severity
Recent Authentication Bypass Using an Alternate Path or Channel vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.7 High severity
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