CVE-2026-74800

CRITICALPre-NVD 9.09.0—
EchelonGraph scoreHIGH confidence

Score 9.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-17. a secondary CVSS source baseline 9.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
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: None knownExposed: 0

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

SiYuan before v3.7.4 fails to set Content-Disposition and X-Content-Type-Options headers when serving arbitrary file assets, allowing stored cross-site scripting attacks. Authenticated attackers can upload HTML files as assets and execute scripts with full kernel API access when the workspace owner opens the asset link.

CVSS v3
9.0
EG Score
9.0(high)
EG Risk
45(Track)
EG Risk 45/100SSVC: 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%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
21%
KEV
Not listed

Published

August 17, 2026

Last Modified

August 17, 2026

Advisory Details (2)

Auto-updated Aug 17, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

SiYuan before v3.7.4 Stored XSS via assets endpoint | Advisories | VulnCheck

https://www.vulncheck.com/advisories/siyuan-before-stored-xss-via-assets-endpoint
github Patch Available🟡 PoC Available

Stored XSS via arbitrary-file assets served same-origin without Content-Disposition or X-Content-Type-Options, escalating to full kernel API access · Advisory · siyuan-note/siyuan · GitHub

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-mjf3-jwmf-r6wf

Vendor Advisories for CVE-2026-74800(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 34× in last 7d / 34× 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. 2026-08-21 06:46 UTCGHSA enrichment
  2. 2026-08-21 02:43 UTCEG score recompute
  3. 2026-08-21 02:43 UTCGHSA enrichment
  4. 2026-08-20 22:56 UTCEPSS rescore
  5. 2026-08-20 22:40 UTCGHSA enrichment
  6. 2026-08-20 18:37 UTCGHSA enrichment
  7. 2026-08-20 14:34 UTCGHSA enrichment
  8. 2026-08-20 10:31 UTCGHSA enrichment
  9. 2026-08-20 06:29 UTCGHSA enrichment
  10. 2026-08-20 02:26 UTCGHSA enrichment
  11. 2026-08-19 22:23 UTCGHSA enrichment
  12. 2026-08-19 18:17 UTCEG score recompute
  13. 2026-08-19 18:17 UTCGHSA enrichment
  14. 2026-08-19 17:04 UTCEPSS rescore
  15. 2026-08-19 13:15 UTCGHSA enrichment
  16. 2026-08-19 09:12 UTCGHSA enrichment
  17. 2026-08-19 05:08 UTCGHSA enrichment
  18. 2026-08-19 01:05 UTCGHSA enrichment
  19. 2026-08-18 21:02 UTCGHSA enrichment
  20. 2026-08-18 16:59 UTCEG score recompute
  21. 2026-08-18 16:59 UTCGHSA enrichment
  22. 2026-08-18 13:49 UTCEPSS rescore
  23. 2026-08-18 13:49 UTCEPSS rescore
  24. 2026-08-18 12:45 UTCGHSA enrichment
  25. 2026-08-18 08:41 UTCGHSA enrichment
Show 9 more
  1. 2026-08-18 04:38 UTCGHSA enrichment
  2. 2026-08-18 00:34 UTCGHSA enrichment
  3. 2026-08-17 20:26 UTCGHSA enrichment
  4. 2026-08-17 16:23 UTCGHSA enrichment
  5. 2026-08-17 15:45 UTCEG score recompute
  6. 2026-08-17 15:45 UTCGHSA enrichment
  7. 2026-08-17 11:42 UTCEG score recompute
  8. 2026-08-17 11:13 UTCEG score recompute
  9. 2026-08-17 11:12 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-74800?
CVE-2026-74800 is a critical vulnerability published on August 17, 2026. SiYuan before v3.7.4 fails to set Content-Disposition and X-Content-Type-Options headers when serving arbitrary file assets, allowing stored cross-site scripting attacks. Authenticated attackers can upload HTML files as assets and execute scripts with full kernel API access when the workspace owner…
When was CVE-2026-74800 disclosed?
CVE-2026-74800 was first published in the National Vulnerability Database on August 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-74800 actively exploited?
CVE-2026-74800 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 78.6% of all scored CVEs.
What is the CVSS score of CVE-2026-74800?
CVE-2026-74800 has a CVSS v3 base score of 9.0 (NVD).
How do I remediate CVE-2026-74800?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-74800, 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-2026-74800

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