What’s Vulnerable › Vulnerabilities

CVE-2026-40514: SmarterTools SmarterMail < Build 9610 Cryptographic Weakness via Weak RNG

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-27 · updated 2026-10-26
• Weakness: CWE-338

Description

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.

Affected products

• SmarterTools SmarterMail: before 100.0.9610 — fixed in 100.0.9610

How to fix

Upgrade to a fixed version: SmarterTools SmarterMail 100.0.9610. Check the vendor advisory for mitigations.

References

• https://www.smartertools.com/smartermail/release-notes/current
• https://www.vulncheck.com/advisories/smartertools-smartermail-build-9610-cryptographic-weakness-via-weak-rng

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