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SmartermailApplication · Smartertools

CVE-2026-40514

CRITICAL · 9.1 CVSS v3.1 Published 2026-04-27
Fix available
A fix is available. Upgrade to 100.0.9610 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
SmarterTools SmarterMail builds prior to 9610 contain a cryptographic weakness in the file and email sharing endpoints that use DES-CBC encryption with keys and initialization vectors derived from System.Random seeded with insufficient entropy, reducing the seed space to approximately 19,000 possible values. An unauthenticated attacker can use the attachment download endpoint as an oracle to determine the seed in use and derive encryption keys and initialization vectors to forge sharing tokens for arbitrary emails, attachments, or file storage contents without prior access to the targeted content.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

SmarterMail builds prior to 9610 use DES-CBC encryption for file and email sharing endpoints where keys and initialization vectors are derived from System.Random with insufficient entropy, collapsing the seed space to approximately 19,000 possible values. An unauthenticated attacker can abuse the attachment download endpoint as an oracle to recover the seed, derive encryption keys, and forge valid sharing tokens for any email, attachment, or file storage content.

MitigationUpgrade to SmarterMail build 9610 or later which implements proper cryptographic random number generation. If immediate upgrade is not possible, disable or restrict public sharing features as a compensating control.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SmartermailApplication
Affected:< 100.0.9610

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check SmarterMail build version
    Locate the SmarterMail installation and check the build number. In the web interface, this is typically shown in the footer or in Help > About. If using command line, check the service info or installation directory for version files.
    Affected if The build number is less than 9610 (e.g., 9609, 9500, etc.)
  2. Verify sharing features are enabled
    Log into the SmarterMail admin interface and navigate to Settings > Sharing (or similar section depending on version). Check if file sharing, email sharing, or attachment sharing options are enabled for users or domains.
    Affected if Public or user-initiated sharing features are enabled and accessible to unauthenticated users
  3. Inspect sharing endpoint accessibility
    Test access to the attachment download/sharing endpoints without authentication. Common patterns include /sharing/download, /attachments/download, or similar URL structures that accept sharing tokens.
    Affected if The sharing download endpoints are reachable without authentication and accept token parameters
  4. Check encryption configuration for sharing
    Review the SmarterMail configuration files (typically in the installation directory under Config or Settings folders) for sharing-related settings. Look for DES or CBC cipher configurations.
    Affected if DES-CBC encryption is configured for sharing functionality (prior to build 9610)
  5. Review System.Random usage in logs
    Examine SmarterMail logs for any errors or indicators related to encryption, sharing token validation, or cryptographic operations. May require enabling verbose logging.
    Affected if Sharing functionality is actively being used and the server is vulnerable

You are affected if SmarterMail build is below 9610 AND sharing features are enabled, allowing unauthenticated access to the vulnerable DES-CBC encrypted sharing endpoints.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 100.0.9610 or later
Fixed in 100.0.9610
Interim mitigation

Upgrade to SmarterMail build 9610 or later which implements proper cryptographic random number generation. If immediate upgrade is not possible, disable or restrict public sharing features as a compensating control.

Recommended fix High confidence

100.0.9610

  1. Upgrade SmarterMail to version 100.0.9610 or later to resolve the weak PRNG (System.Random) vulnerability in DES-CBC encryption used for file and email sharing endpoints
  2. After upgrading, verify that sharing tokens are being generated using a cryptographically secure random number generator
  3. Review any shared links or tokens created prior to the upgrade and regenerate them if possible to ensure they use the fixed encryption

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Smartermail Scoped from the published advisory
  • Consultation6.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
34.0 hours of engineering $6,000
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40514 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data