CVE-2026-55254: Ncalc

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

NCalc is a fast, lightweight expression evaluator for .NET. Prior to 6.1.1, the factorial operator implementation in src/NCalc.Core/Helpers/MathHelper.cs permits specially crafted expressions with extremely large factorial operands, causing excessive CPU consumption or a non-terminating loop due to integer overflow in the factorial calculation logic when applications evaluate untrusted expressions. This issue is fixed in version 6.1.1.

Affected products

• Ncalc Ncalc: before 6.1.1 (fixed in 6.1.1)

Published 2026-07-17. Last modified 2026-08-18.