CVE-2026-55254

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. 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, nvd
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 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
6.5
EG Score
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

July 17, 2026

Last Modified

August 18, 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 7× in last 7d / 43× 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. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-10 09:35 UTCEPSS rescore
  3. 2026-09-08 22:01 UTCEPSS rescore
  4. 2026-09-07 23:59 UTCEG score recompute
  5. 2026-09-07 16:01 UTCEPSS rescore
  6. 2026-09-06 13:47 UTCEPSS rescore
  7. 2026-09-05 20:26 UTCEG score recompute
  8. 2026-09-04 05:06 UTCEPSS rescore
  9. 2026-09-02 14:12 UTCEPSS rescore
  10. 2026-09-01 13:54 UTCEPSS rescore
  11. 2026-09-01 04:40 UTCEPSS rescore
  12. 2026-08-31 04:52 UTCEG score recompute
  13. 2026-08-30 19:17 UTCEPSS rescore
  14. 2026-08-30 03:14 UTCEG score recompute
  15. 2026-08-30 01:22 UTCEPSS rescore
  16. 2026-08-28 21:41 UTCEPSS rescore
  17. 2026-08-27 14:25 UTCEPSS rescore
  18. 2026-08-27 13:44 UTCEG score recompute
  19. 2026-08-26 14:46 UTCEPSS rescore
  20. 2026-08-26 11:55 UTCEG score recompute
  21. 2026-08-25 13:49 UTCEPSS rescore
  22. 2026-08-25 08:44 UTCEG score recompute
  23. 2026-08-23 04:31 UTCEG score recompute
  24. 2026-08-23 00:19 UTCEPSS rescore
  25. 2026-08-22 02:52 UTCEG score recompute
Show 64 more
  1. 2026-08-21 23:49 UTCEPSS rescore
  2. 2026-08-21 01:03 UTCEG score recompute
  3. 2026-08-20 22:55 UTCEPSS rescore
  4. 2026-08-19 23:25 UTCEG score recompute
  5. 2026-08-19 17:04 UTCEPSS rescore
  6. 2026-08-18 16:00 UTCEG score recompute▲ 1.70
  7. 2026-08-18 15:59 UTCNVD updateCVSS v3 → 6.5
  8. 2026-08-18 13:48 UTCEPSS rescore
  9. 2026-08-17 15:34 UTCEG score recompute
  10. 2026-08-17 13:47 UTCEPSS rescore
  11. 2026-08-16 14:56 UTCEPSS rescore
  12. 2026-08-16 13:56 UTCEG score recompute
  13. 2026-08-16 02:14 UTCEPSS rescore
  14. 2026-08-15 12:18 UTCEG score recompute
  15. 2026-08-15 01:30 UTCEPSS rescore
  16. 2026-08-14 10:39 UTCEG score recompute
  17. 2026-08-13 22:00 UTCEPSS rescore
  18. 2026-08-13 09:01 UTCEG score recompute
  19. 2026-08-12 13:51 UTCEPSS rescore
  20. 2026-08-12 07:23 UTCEG score recompute
  21. 2026-08-11 05:42 UTCEG score recompute
  22. 2026-08-11 00:00 UTCEPSS rescore
  23. 2026-08-10 04:04 UTCEG score recompute
  24. 2026-08-09 13:46 UTCEPSS rescore
  25. 2026-08-09 02:26 UTCEG score recompute
  26. 2026-08-08 16:37 UTCEPSS rescore
  27. 2026-08-08 00:48 UTCEG score recompute
  28. 2026-08-06 23:09 UTCEG score recompute
  29. 2026-08-06 13:47 UTCEPSS rescore
  30. 2026-08-05 21:31 UTCEG score recompute
  31. 2026-08-05 19:17 UTCEPSS rescore
  32. 2026-08-04 19:53 UTCEG score recompute
  33. 2026-08-04 15:10 UTCEPSS rescore
  34. 2026-08-04 10:39 UTCEPSS rescore
  35. 2026-08-03 18:15 UTCEG score recompute
  36. 2026-08-03 10:36 UTCEPSS rescore
  37. 2026-08-02 16:11 UTCEG score recompute
  38. 2026-08-02 02:27 UTCEPSS rescore
  39. 2026-08-01 14:32 UTCEG score recompute
  40. 2026-08-01 04:16 UTCEPSS rescore
  41. 2026-07-31 12:54 UTCEG score recompute
  42. 2026-07-30 16:28 UTCEPSS rescore
  43. 2026-07-30 11:14 UTCEG score recompute
  44. 2026-07-30 01:30 UTCEPSS rescore
  45. 2026-07-29 09:35 UTCEG score recompute
  46. 2026-07-28 15:37 UTCEPSS rescore
  47. 2026-07-28 07:56 UTCEG score recompute
  48. 2026-07-27 06:14 UTCEG score recompute
  49. 2026-07-26 14:54 UTCEPSS rescore
  50. 2026-07-26 04:34 UTCEG score recompute
  51. 2026-07-25 14:18 UTCEPSS rescore
  52. 2026-07-24 14:18 UTCEPSS rescore
  53. 2026-07-23 14:18 UTCEPSS rescore
  54. 2026-07-23 03:20 UTCEG score recompute
  55. 2026-07-23 00:12 UTCEG score recompute
  56. 2026-07-22 14:08 UTCEPSS rescore
  57. 2026-07-21 15:25 UTCEPSS rescore
  58. 2026-07-20 17:08 UTCEPSS rescore
  59. 2026-07-19 14:31 UTCEPSS rescore
  60. 2026-07-19 14:31 UTCEPSS rescore
  61. 2026-07-19 02:29 UTCEPSS rescore
  62. 2026-07-17 22:02 UTCEG score recompute
  63. 2026-07-17 20:15 UTCEG score recompute
  64. 2026-07-17 20:14 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

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 August 18, 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 0% probability of exploitation in the next 30 days, which ranks it in the top 91.1% of all scored CVEs.
What is the CVSS score of CVE-2026-55254?
CVE-2026-55254 has a CVSS v3 base score of 6.5 (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.

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