{"id":"CVE-2026-55254","aliases":["GHSA-3w5p-95mh-gq75"],"url":"https://o3.security/vulnerability/CVE-2026-55254","summary":"NCalc: Denial of Service via Unbounded and Non-Terminating Factorial Evaluation","details":"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.","published":"2026-07-17T19:55:16.728Z","modified":"2026-08-20T03:54:29.799400108Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H"},"epss":{"score":0.00191,"percentile":0.08946,"asOf":"2026-09-12"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"NuGet","name":"NCalc.Core","fixedVersion":"6.1.1"},{"ecosystem":"NuGet","name":"NCalcSync","fixedVersion":"6.1.1"}],"fix":{"url":"https://github.com/ncalc/ncalc/commit/eeb6155ee1899b1fdf2cda3da35a4f0ca93ffd6a","label":"ncalc/ncalc@eeb6155"},"references":[{"type":"WEB","url":"https://github.com/ncalc/ncalc/releases/tag/v6.1.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55254.json"},{"type":"ADVISORY","url":"https://github.com/ncalc/ncalc/security/advisories/GHSA-3w5p-95mh-gq75"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55254"},{"type":"FIX","url":"https://github.com/ncalc/ncalc/commit/eeb6155ee1899b1fdf2cda3da35a4f0ca93ffd6a"},{"type":"FIX","url":"https://github.com/ncalc/ncalc/pull/575"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-20T03:54:29.799400108Z"}}