SmarterTools SmarterMail: authentication bypass flaw under attack

What is affected

SmarterTools SmarterMail is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

SmarterTools SmarterMail contains an authentication bypass using an alternate path or channel 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. This could allow an unauthenticated attacker to supply a target administrator username and a new password to reset the account, resulting in full administrative compromise of the SmarterMail instance.

What an attacker can do

This is a authentication bypass flaw. It lets an attacker get in without a valid username and password and act as a legitimate user, often as an administrator.

How it is reached

Over the internet or network

Access the attacker needs

No account needed

Does the victim have to do something?

No, works without the victim doing anything

CISA records this vulnerability as known to be used in ransomware campaigns: attackers use it to get in, then encrypt files and demand payment.

What to do

1. At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
2. If you administer SmarterTools SmarterMail at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
3. If the product is past its support date and no fix exists, take it off the internet or retire it.

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 advisories and fixes

• smartertools.comwww.smartertools.com/smartermail/release-notes/current

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on January 26, 2026, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by February 16, 2026, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 97% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99.9% of all scored vulnerabilities.

Its CVSS severity score is 9.3 out of 10 (critical), as recorded in the US National Vulnerability Database.

Technical 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.