Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M

CVE-2026-55254NCalc: Denial of Service via Unbounded and Non-Terminating Factorial Evaluation

Medium 4.8

In plain English

A medium-severity resource allocation without limits in ncalc from ncalc. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.8Medium

Exploit odds (30 days)0.3%top 78.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
NuGet	ncalc.core	6.1.1	GHSA-3w5p-95mh-gq75
NuGet	ncalcsync	6.1.1	GHSA-3w5p-95mh-gq75

Affected products (as reported)

Vendor	Product	Versions
ncalc	ncalc	< 6.1.1

Weakness: CWE-770, CWE-190 · Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H

References

https://github.com/ncalc/ncalc/security/advisories/GHSA-3w5p-95mh-gq75 x_refsource_CONFIRM
https://github.com/ncalc/ncalc/pull/575 x_refsource_MISC
https://github.com/ncalc/ncalc/commit/eeb6155ee1899b1fdf2cda3da35a4f0ca93ffd6a x_refsource_MISC
https://github.com/ncalc/ncalc/releases/tag/v6.1.1 x_refsource_MISC