CVE-2026-84803

CRITICALPre-NVD 9.09.0—
EchelonGraph scoreHIGH confidence

Score 9.0 from GitHub Security Advisory (severity: HIGH) published 2026-09-02. a secondary CVSS source baseline 9.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
9.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.0Exploit: Elevated riskExposed: 0

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

SiYuan before v3.8.2 contains a stored cross-site scripting vulnerability in asset serving due to an incomplete extension blocklist that misses script-capable file types. Attackers can upload files with extensions like .xht, .ehtml, .xsl, .xbl, or .rdf that resolve to executable media types and execute JavaScript to steal API tokens and compromise workspaces.

CVSS v3
9.0
EG Score
9.0(high)
EG Risk
57(Track*)
EG Risk 57/100SSVC: 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
Severity90% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

September 2, 2026

Last Modified

September 2, 2026

Advisory Details (2)

Auto-updated Sep 2, 2026
Patch available. Sources: github.
generic

SiYuan before v3.8.2 Stored XSS via incomplete asset blocklist | Advisories | VulnCheck

https://www.vulncheck.com/advisories/siyuan-before-3.8.2-stored-xss-via-incomplete-asset-blocklist
github Patch Available

Incomplete Asset Blocklist Bypasses the GHSA-mjf3-jwmf-r6wf Fix (Stored XSS, API Token Theft) · Advisory · siyuan-note/siyuan · GitHub

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-7h8j-qw37-w46g

Vendor Advisories for CVE-2026-84803(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 54× in last 7d / 178× 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 178 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-84803?
CVE-2026-84803 is a critical vulnerability published on September 2, 2026. SiYuan before v3.8.2 contains a stored cross-site scripting vulnerability in asset serving due to an incomplete extension blocklist that misses script-capable file types. Attackers can upload files with extensions like .xht, .ehtml, .xsl, .xbl, or .rdf that resolve to executable media types and…
When was CVE-2026-84803 disclosed?
CVE-2026-84803 was first published in the National Vulnerability Database on September 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84803 actively exploited?
CVE-2026-84803 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 65.7% of all scored CVEs.
What is the CVSS score of CVE-2026-84803?
CVE-2026-84803 has a CVSS v3 base score of 9.0 (NVD).
How do I remediate CVE-2026-84803?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84803, 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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