CVE-2026-66394

HIGHPre-NVD 8.78.7—
EchelonGraph scoreMEDIUM confidence

Score 8.7 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-27. a secondary CVSS source baseline 8.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
8.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.7Exploit: Elevated riskExposed: 0

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

SiYuan before v3.7.3 contains stored and reflected cross-site scripting vulnerabilities in SVG sanitization that allows authenticated attackers to execute scripts by bypassing the HTML parser-based cleaner. Attackers can hide script tags within desc, style, or noscript elements which the HTML parser treats as raw text but browsers interpret as executable SVG content when served as image/svg+xml, enabling script execution in the application origin.

CVSS v3
8.7
EG Score
8.7(medium)
EG Risk
55(Track)
EG Risk 55/100SSVC: 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
Severity87% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
18%
KEV
Not listed

Published

July 27, 2026

Last Modified

July 28, 2026

Advisory Details (2)

Auto-updated Jul 27, 2026
Patch available. Sources: github.
generic

SiYuan before v3.7.3 Stored and Reflected XSS via SVG Sanitizer Bypass | Advisories | VulnCheck

https://www.vulncheck.com/advisories/siyuan-before-stored-and-reflected-xss-via-svg-sanitizer-bypass
github Patch Available

Stored and reflected XSS in SiYuan through an SVG sanitizer bypass · Advisory · siyuan-note/siyuan · GitHub

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f

Vendor Advisories for CVE-2026-66394(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 108× 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 127 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-66394?
CVE-2026-66394 is a high vulnerability published on July 27, 2026. SiYuan before v3.7.3 contains stored and reflected cross-site scripting vulnerabilities in SVG sanitization that allows authenticated attackers to execute scripts by bypassing the HTML parser-based cleaner. Attackers can hide script tags within desc, style, or noscript elements which the HTML…
When was CVE-2026-66394 disclosed?
CVE-2026-66394 was first published in the National Vulnerability Database on July 27, 2026, with the most recent update on July 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66394 actively exploited?
CVE-2026-66394 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 81.6% of all scored CVEs.
What is the CVSS score of CVE-2026-66394?
CVE-2026-66394 has a CVSS v3 base score of 8.7 (NVD).
How do I remediate CVE-2026-66394?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66394, 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

Explore the affected products and dependency analysis for CVE-2026-66394

Explore →

Is Your Infrastructure Affected by CVE-2026-66394?

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

Start Free Scan →Browse All CVEs