CVE-2026-100634

MEDIUMPre-NVD 4.74.7—
EchelonGraph scoreHIGH confidence

Score 4.7 from GitHub Security Advisory published 2026-09-26. A secondary CVSS source baseline 4.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
4.7EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 4.7Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

SiYuan before v3.8.4 does not validate the sender or restrict recipients in the 'siyuan-send-windows' IPC handler of the Electron main process (app/electron/main.js). The handler ignores event.sender and forwards any received payload to every BrowserWindow returned by BrowserWindow.getAllWindows(), including windows belonging to other opened workspaces. A renderer connected to an attacker-controlled remote kernel can therefore send {cmd: "lockscreenByMode"} and have it delivered across the workspace boundary; a sibling workspace window whose lockScreenMode is set to 1 invokes lockScreen(). Repeated messages allow the remote workspace to repeatedly lock unrelated local workspace windows, causing a limited denial of service. No confidentiality, integrity, or code-execution impact was observed.

CVSS v3
4.7
EG Score
4.7MEDIUMhigh confidence
EG Risk
37
EG Risk 37/100CISA SSVC

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
Severity47% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
38th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 26, 2026

Last Modified

September 30, 2026

Advisory Details (3)

Auto-updated Sep 26, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
generic

SiYuan before v3.8.4 Missing Authorization via siyuan-send-windows | Advisories | VulnCheck

https://www.vulncheck.com/advisories/siyuan-before-3.8.4-missing-authorization-via-siyuan-send-windows
github_commit

commit 8641553a1f07 (siyuan-note/siyuan)

Fix landed in siyuan-note/siyuan commit 8641553a1f07 — awaiting tagged release

https://github.com/siyuan-note/siyuan/commit/8641553a1f07374001902d3ce773285db1292b2d
github Patch Available🟡 PoC Available

Unrestricted siyuan-send-windows Broadcast Lacks Sender and Workspace Authorization · Advisory · siyuan-note/siyuan · GitHub

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-wxp7-xpq8-8xpm

Vendor Advisories for CVE-2026-100634(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 23× in last 7d / 28× 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. 2026-10-04 09:34 UTCEG score recompute
  2. 2026-10-04 09:34 UTCGHSA enrichment
  3. 2026-10-03 14:25 UTCEPSS rescore
  4. 2026-10-03 10:35 UTCEG score recompute
  5. 2026-10-03 10:35 UTCGHSA enrichment
  6. 2026-10-02 11:33 UTCEG score recompute
  7. 2026-10-02 11:32 UTCGHSA enrichment
  8. 2026-10-01 19:49 UTCEPSS rescore
  9. 2026-10-01 12:25 UTCEG score recompute
  10. 2026-10-01 12:25 UTCGHSA enrichment
  11. 2026-09-30 15:02 UTCEPSS rescore
  12. 2026-09-30 13:24 UTCEG score recompute
  13. 2026-09-30 13:24 UTCGHSA enrichment
  14. 2026-09-30 13:13 UTCEG score recompute
  15. 2026-09-30 13:13 UTCGHSA enrichment
  16. 2026-09-30 10:28 UTCEG score recompute
  17. 2026-09-30 10:28 UTCGHSA enrichment
  18. 2026-09-29 15:20 UTCEPSS rescore
  19. 2026-09-29 11:28 UTCEG score recompute
  20. 2026-09-29 11:28 UTCGHSA enrichment
  21. 2026-09-28 13:50 UTCEPSS rescore
  22. 2026-09-28 12:30 UTCEG score recompute
  23. 2026-09-28 12:30 UTCGHSA enrichment
  24. 2026-09-27 13:32 UTCEG score recompute
  25. 2026-09-27 13:32 UTCGHSA enrichment
Show 3 more
  1. 2026-09-26 14:34 UTCEG score recompute
  2. 2026-09-26 13:39 UTCEG score recompute
  3. 2026-09-26 13:30 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-100634?
CVE-2026-100634 is a medium vulnerability published on September 26, 2026. SiYuan before v3.8.4 does not validate the sender or restrict recipients in the 'siyuan-send-windows' IPC handler of the Electron main process (app/electron/main.js). The handler ignores event.sender and forwards any received payload to every BrowserWindow returned by BrowserWindow.getAllWindows(),…
When was CVE-2026-100634 disclosed?
CVE-2026-100634 was first published on September 26, 2026, with the most recent update on September 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100634 actively exploited?
CVE-2026-100634 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (38th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-100634?
CVE-2026-100634 has a CVSS base score of 4.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-100634?
A fix for CVE-2026-100634 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-100634 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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