CVE-2026-74903

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreHIGH confidence

Score 4.3 from GitHub Security Advisory published 2026-08-18. a secondary CVSS source baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: Elevated riskExposed: 0

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

SiYuan before v3.7.4 contains an insufficient access control vulnerability in the /api/lute/spinBlockDOM endpoint, which is guarded only by CheckAuth middleware instead of CheckAdminRole like its sibling endpoint. Authenticated users with RoleEditor or RoleReader roles can invoke the endpoint to transform arbitrary DOM input, and large payloads cause endpoint starvation through per-path mutex serialization.

CVSS v3
4.3
EG Score
4.3(high)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity43% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
11%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 18, 2026

Advisory Details (2)

Auto-updated Aug 18, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

SiYuan before v3.7.4 Insufficient Access Control via spinBlockDOM | Advisories | VulnCheck

https://www.vulncheck.com/advisories/siyuan-before-insufficient-access-control-via-spinblockdom
github Patch Available🟡 PoC Available

/api/lute/spinBlockDOM Accessible to All Authenticated Roles Without Admin Gate or Input Size Limit · Advisory · siyuan-note/siyuan · GitHub

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3j8q-5c8c-grwm

Vendor Advisories for CVE-2026-74903(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 13× in last 7d / 13× 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. 2026-08-20 22:56 UTCEPSS rescore
  2. 2026-08-20 19:56 UTCGHSA enrichment
  3. 2026-08-19 18:16 UTCEG score recompute
  4. 2026-08-19 18:16 UTCGHSA enrichment
  5. 2026-08-19 17:04 UTCEPSS rescore
  6. 2026-08-18 15:23 UTCEG score recompute
  7. 2026-08-18 15:22 UTCGHSA enrichment
  8. 2026-08-18 15:15 UTCEG score recompute
  9. 2026-08-18 15:15 UTCGHSA enrichment
  10. 2026-08-18 12:36 UTCEG score recompute
  11. 2026-08-18 12:35 UTCGHSA enrichment
  12. 2026-08-18 11:29 UTCEG score recompute
  13. 2026-08-18 11:29 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-74903?
CVE-2026-74903 is a medium vulnerability published on August 18, 2026. SiYuan before v3.7.4 contains an insufficient access control vulnerability in the /api/lute/spinBlockDOM endpoint, which is guarded only by CheckAuth middleware instead of CheckAdminRole like its sibling endpoint. Authenticated users with RoleEditor or RoleReader roles can invoke the endpoint to…
When was CVE-2026-74903 disclosed?
CVE-2026-74903 was first published in the National Vulnerability Database 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-2026-74903 actively exploited?
CVE-2026-74903 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 88.5% of all scored CVEs.
What is the CVSS score of CVE-2026-74903?
CVE-2026-74903 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-74903?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-74903, 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

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