CVE-2026-87809

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-09. a secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

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

Siyuan before v3.8.2 fails to apply publish-access filtering to embedded blocks before rendering in the /api/export/preview and /api/lute/copyStdMarkdown endpoints. Attackers with reader access can retrieve the full rendered content of private, hidden, or publish-disabled blocks by accessing public documents containing embed queries that select those blocks.

CVSS v3
6.5
EG Score
6.5(high)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
11%
KEV
Not listed

Published

September 9, 2026

Last Modified

September 18, 2026

Advisory Details (2)

Auto-updated Sep 9, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

Siyuan before v3.8.2 Information Disclosure via Export Preview | Advisories | VulnCheck

https://www.vulncheck.com/advisories/siyuan-before-3.8.2-information-disclosure-via-export-preview
github Patch Available🟡 PoC Available

Reader-capable /api/export/preview and /api/lute/copyStdMarkdown expand publish-disabled embeds before publication filtering · Advisory · siyuan-note/siyuan · GitHub

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-8wx4-fvqw-f5f8

Vendor Advisories for CVE-2026-87809(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 22× in last 7d / 35× 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. 2026-09-20 20:16 UTCEPSS rescore
  2. 2026-09-20 14:01 UTCGHSA enrichment
  3. 2026-09-19 16:17 UTCEG score recompute
  4. 2026-09-19 16:17 UTCGHSA enrichment
  5. 2026-09-18 19:28 UTCEPSS rescore
  6. 2026-09-18 18:33 UTCEG score recompute
  7. 2026-09-18 18:33 UTCGHSA enrichment
  8. 2026-09-18 17:30 UTCEG score recompute
  9. 2026-09-18 17:30 UTCGHSA enrichment
  10. 2026-09-18 00:27 UTCEG score recompute
  11. 2026-09-18 00:27 UTCGHSA enrichment
  12. 2026-09-17 19:32 UTCEPSS rescore
  13. 2026-09-17 02:43 UTCEG score recompute
  14. 2026-09-17 02:43 UTCGHSA enrichment
  15. 2026-09-16 14:09 UTCEPSS rescore
  16. 2026-09-16 05:15 UTCEPSS rescore
  17. 2026-09-16 04:56 UTCGHSA enrichment
  18. 2026-09-15 07:12 UTCEG score recompute
  19. 2026-09-15 07:12 UTCGHSA enrichment
  20. 2026-09-15 03:12 UTCEPSS rescore
  21. 2026-09-14 09:28 UTCEG score recompute
  22. 2026-09-14 09:28 UTCGHSA enrichment
  23. 2026-09-13 11:45 UTCEG score recompute
  24. 2026-09-13 11:45 UTCGHSA enrichment
  25. 2026-09-12 14:01 UTCGHSA enrichment
Show 10 more
  1. 2026-09-11 16:17 UTCEG score recompute
  2. 2026-09-11 16:17 UTCGHSA enrichment
  3. 2026-09-11 14:53 UTCEPSS rescore
  4. 2026-09-11 14:53 UTCEPSS rescore
  5. 2026-09-10 18:32 UTCGHSA enrichment
  6. 2026-09-09 20:46 UTCEG score recompute
  7. 2026-09-09 20:45 UTCGHSA enrichment
  8. 2026-09-09 12:25 UTCEG score recompute
  9. 2026-09-09 11:30 UTCEG score recompute
  10. 2026-09-09 11:29 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-87809?
CVE-2026-87809 is a medium vulnerability published on September 9, 2026. Siyuan before v3.8.2 fails to apply publish-access filtering to embedded blocks before rendering in the /api/export/preview and /api/lute/copyStdMarkdown endpoints. Attackers with reader access can retrieve the full rendered content of private, hidden, or publish-disabled blocks by accessing public…
When was CVE-2026-87809 disclosed?
CVE-2026-87809 was first published in the National Vulnerability Database on September 9, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-87809 actively exploited?
CVE-2026-87809 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 88.7% of all scored CVEs.
What is the CVSS score of CVE-2026-87809?
CVE-2026-87809 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-87809?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-87809, 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-2026-87809

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