CVE-2026-55254

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

MEDIUM
6.5
CVSS Score
Published: July 17, 2026 at 07:55 PM UTC
Updated: August 18, 2026 at 03:55 PM UTC
1 product affected across 1 vendorNcalc

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 6.1.1
Affected range stops below 6.1.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMPatchVendor Advisory
Source: cverecord
https://github.com/ncalc/ncalc/security/advisories/GHSA-3w5p-95mh-gq75
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/ncalc/ncalc/pull/575
x_refsource_MISCProductRelease Notes
Source: cverecord
https://github.com/ncalc/ncalc/releases/tag/v6.1.1

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
ADJACENT_NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-770CWE-190

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