CVE-2026-55254

MEDIUMPre-NVD 4.84.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 91% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
4.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
4.8
EG Score
4.8(medium)
EG Risk
22(Track)
EG Risk 22/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity48% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
8.7%
KEV
Not listed

Published

July 17, 2026

Last Modified

July 23, 2026

Advisory Details (4)

Auto-updated Jul 17, 2026
Patch available. Sources: github, github_commit, github_pr, github_release.
github Patch Available

Denial of Service via Unbounded and Non-Terminating Factorial Evaluation in NCalc · Advisory · ncalc/ncalc · GitHub

https://github.com/ncalc/ncalc/security/advisories/GHSA-3w5p-95mh-gq75
github_release Patch Available

v6.1.1

Patch available: ncalc/ncalc v6.1.1

https://github.com/ncalc/ncalc/releases/tag/v6.1.1
github_pr Patch Available

Fix factorial input bounds and overflow handling

Patch available: ncalc/ncalc v6.1.1 (PR #575 merged 2026-06-11)

https://github.com/ncalc/ncalc/pull/575
github_commit Patch Available

commit eeb6155ee189 (ncalc/ncalc)

Patch available: ncalc/ncalc v6.1.1 (contains commit eeb6155ee189)

https://github.com/ncalc/ncalc/commit/eeb6155ee1899b1fdf2cda3da35a4f0ca93ffd6a

Affected Packages

(2 across 1 ecosystem)
NuGet(2)
PackageVulnerable rangeFixed inDependents
NCalc.Core4.3.0 ... 6.1.0 (36 versions)6.1.1—
NCalcSync2.0.0 ... 6.1.0 (56 versions)6.1.1—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 12× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 03:20 UTCEG score recompute
  3. 2026-07-23 00:12 UTCEG score recompute
  4. 2026-07-22 14:08 UTCEPSS rescore
  5. 2026-07-21 15:25 UTCEPSS rescore
  6. 2026-07-20 17:08 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 14:31 UTCEPSS rescore
  9. 2026-07-19 02:29 UTCEPSS rescore
  10. 2026-07-17 22:02 UTCEG score recompute
  11. 2026-07-17 20:15 UTCEG score recompute
  12. 2026-07-17 20:14 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-55254?
CVE-2026-55254 is a medium vulnerability published on July 17, 2026. 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…
When was CVE-2026-55254 disclosed?
CVE-2026-55254 was first published in the National Vulnerability Database on July 17, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55254 actively exploited?
CVE-2026-55254 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 8.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-55254?
CVE-2026-55254 has a CVSS v3 base score of 4.8 (NVD).
How do I remediate CVE-2026-55254?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55254, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55254

Explore →

Is Your Infrastructure Affected by CVE-2026-55254?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs