Medium, CVSS 4.8NuGetPublished
NCalc: Denial of Service via Unbounded and Non-Terminating Factorial Evaluation
CVE-2026-55254 · GHSA-3w5p-95mh-gq75
- Affected
- NuGet ncalcsync < 6.1.1
- Fixed in
- 6.1.1· Vendor fix available
- Issue
- Impact A denial-of-service (DoS) vulnerability exists in the factorial operator implementation of NCalc. Specially crafted expressions containing extremely large factorial operands can trigger excessive CPU consumption or cause evaluation to enter a non-terminating loop due to integer overflow in the factorial calculation logic. Applications that evaluate untrusted expressions using affected versions of NCalc may be vulnerable to resource exhaustion, potentially resulting in service disruption or application unresponsiveness. This issue can be triggered with expressions such as: Patches The vulnerability has been fixed by adding bounds validation for factorial operands and rejecting unsupported values before evaluation. Users should upgrade to the first release containing the fix from pull request #575. (v6.1.1+) Workarounds If upgrading is not immediately possible: Do not evaluate expressions originating from untrusted users. Validate or sanitize expressions before evaluation and…
Recommended action: Upgrade to 6.1.1 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.