CVE-2026-3663

HIGHNVD 7.17.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.1 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 93% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
7.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.1Exploit: None knownExposed: 0

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

A vulnerability was found in xlnt-community xlnt up to 1.6.1. This issue affects the function xlnt::detail::compound_document_istreambuf::xsgetn of the file source/detail/cryptography/compound_document.cpp of the component XLSX File Parser. Performing a manipulation results in out-of-bounds read. The attack is only possible with local access. The exploit has been made public and could be used. The patch is named 147. It is recommended to apply a patch to fix this issue.

CVSS v3
7.1
EG Score
7.1(medium)
EG Risk
32(Track)
EG Risk 32/100SSVC: 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
Severity71% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
7%
KEV
Not listed

Published

March 7, 2026

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated Aug 4, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
github_pr

Compound document improvements

Fix merged in xlnt-community/xlnt PR #147 on 2026-08-02 — awaiting tagged release

https://github.com/xlnt-community/xlnt/pull/147
generic

[Bug] Heap-buffer-overflow (Read) in compound_document_istreambuf::xsgetn (compound_document.cpp:132) · Issue #139 · xlnt-community/xlnt · GitHub

https://github.com/xlnt-community/xlnt/issues/139
generic

GitHub - xlnt-community/xlnt: :bar_chart: Cross-platform user-friendly xlsx library for C++11+ · GitHub

https://github.com/xlnt-community/xlnt/
generic

0128/xl3/repro at main · oneafter/0128 · GitHub

https://github.com/oneafter/0128/blob/main/xl3/repro

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 25× 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.

Showing the most recent 100 of 175 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
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  11. 2026-09-08 22:00 UTCEPSS rescore
  12. 2026-09-07 16:01 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 23:29 UTCOSV refresh
  16. 2026-09-02 14:12 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-08-30 19:17 UTCEPSS rescore
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  20. 2026-08-28 21:41 UTCEPSS rescore
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  1. 2026-08-20 22:55 UTCEPSS rescore
  2. 2026-08-19 17:03 UTCEPSS rescore
  3. 2026-08-17 13:47 UTCEPSS rescore
  4. 2026-08-16 14:56 UTCEPSS rescore
  5. 2026-08-16 12:18 UTCEG score recompute
  6. 2026-08-16 12:18 UTCGHSA enrichment
  7. 2026-08-16 02:14 UTCEPSS rescore
  8. 2026-08-15 01:30 UTCEPSS rescore
  9. 2026-08-14 20:42 UTCGHSA enrichment
  10. 2026-08-14 08:12 UTCEG score recompute
  11. 2026-08-14 08:12 UTCGHSA enrichment
  12. 2026-08-13 22:00 UTCEPSS rescore
  13. 2026-08-12 23:41 UTCEG score recompute
  14. 2026-08-12 23:41 UTCGHSA enrichment
  15. 2026-08-12 13:51 UTCEPSS rescore
  16. 2026-08-11 22:30 UTCEG score recompute
  17. 2026-08-11 22:30 UTCGHSA enrichment
  18. 2026-08-11 13:43 UTCEPSS rescore
  19. 2026-08-11 05:20 UTCEG score recompute
  20. 2026-08-11 05:20 UTCGHSA enrichment
  21. 2026-08-11 00:00 UTCEPSS rescore
  22. 2026-08-10 08:03 UTCGHSA enrichment
  23. 2026-08-09 19:57 UTCEG score recompute
  24. 2026-08-09 19:57 UTCGHSA enrichment
  25. 2026-08-09 13:46 UTCEPSS rescore
  26. 2026-08-09 07:52 UTCGHSA enrichment
  27. 2026-08-08 07:23 UTCGHSA enrichment
  28. 2026-08-07 19:18 UTCEG score recompute
  29. 2026-08-07 19:18 UTCGHSA enrichment
  30. 2026-08-06 20:22 UTCEG score recompute
  31. 2026-08-06 20:22 UTCGHSA enrichment
  32. 2026-08-06 13:46 UTCEPSS rescore
  33. 2026-08-06 02:21 UTCEG score recompute
  34. 2026-08-06 02:21 UTCGHSA enrichment
  35. 2026-08-05 19:17 UTCEPSS rescore
  36. 2026-08-04 15:10 UTCEPSS rescore
  37. 2026-08-04 10:38 UTCEPSS rescore
  38. 2026-08-04 01:46 UTCEG score recompute
  39. 2026-08-04 01:46 UTCGHSA enrichment
  40. 2026-08-03 10:36 UTCEPSS rescore
  41. 2026-08-02 18:33 UTCEG score recompute▲ 3.80
  42. 2026-08-02 18:33 UTCGHSA enrichment
  43. 2026-08-02 02:27 UTCEPSS rescore
  44. 2026-08-01 04:16 UTCEPSS rescore
  45. 2026-07-30 16:28 UTCEPSS rescore
  46. 2026-07-30 01:30 UTCEPSS rescore
  47. 2026-07-27 14:13 UTCEPSS rescore
  48. 2026-07-26 14:54 UTCEPSS rescore
  49. 2026-07-26 14:54 UTCEPSS rescore
  50. 2026-07-25 14:18 UTCEPSS rescore
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  52. 2026-07-24 14:17 UTCEPSS rescore
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  54. 2026-07-23 14:18 UTCEPSS rescore
  55. 2026-07-23 14:18 UTCEPSS rescore
  56. 2026-07-23 03:10 UTCEG score recompute
  57. 2026-07-22 14:08 UTCEPSS rescore
  58. 2026-07-21 15:24 UTCEPSS rescore
  59. 2026-07-20 17:08 UTCEPSS rescore
  60. 2026-07-19 14:31 UTCEPSS rescore
  61. 2026-07-18 10:04 UTCEPSS rescore
  62. 2026-07-16 17:03 UTCEPSS rescore
  63. 2026-07-16 08:49 UTCOSV refresh
  64. 2026-07-15 16:57 UTCEPSS rescore
  65. 2026-07-15 16:57 UTCEPSS rescore
  66. 2026-07-15 02:00 UTCEPSS rescore
  67. 2026-07-13 22:30 UTCEPSS rescore
  68. 2026-07-13 06:13 UTCEPSS rescore
  69. 2026-07-13 06:13 UTCEPSS rescore
  70. 2026-07-11 08:27 UTCEPSS rescore
  71. 2026-07-09 19:10 UTCEPSS rescore
  72. 2026-07-08 15:15 UTCEPSS rescore
  73. 2026-07-07 13:46 UTCEPSS rescore
  74. 2026-07-06 16:27 UTCEPSS rescore
  75. 2026-07-06 16:27 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-3663?
CVE-2026-3663 is a high vulnerability published on March 7, 2026. A vulnerability was found in xlnt-community xlnt up to 1.6.1. This issue affects the function xlnt::detail::compounddocumentistreambuf::xsgetn of the file source/detail/cryptography/compound_document.cpp of the component XLSX File Parser. Performing a manipulation results in out-of-bounds read. The…
When was CVE-2026-3663 disclosed?
CVE-2026-3663 was first published in the National Vulnerability Database on March 7, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-3663 actively exploited?
CVE-2026-3663 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 93.2% of all scored CVEs.
What is the CVSS score of CVE-2026-3663?
CVE-2026-3663 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2026-3663?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-3663, 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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