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TI-2026-85954 Aliases CVE-2026-123492GHSA-pxf5-vpcp-gg52

Nil pointer dereference in SiYuan lets attackers crash the kernel

Priority LOW 30CWE-476Published · Updated

Key facts

Attack vector
Network
Privileges required
High
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-476.

Summary

SiYuan before 3.8.9 contains a nil pointer dereference (CWE-476) in privateCacheMiddleware. An authenticated attacker with a valid API token can crash the kernel process by reading a nonexistent MCP resource in an initialized MCP session, which interrupts service.

Written with Claude Haiku 5.5 from the sources below · 2026-11-08

Description from the CNA

SiYuan before 3.8.9 contains a nil pointer dereference vulnerability in privateCacheMiddleware that allows authenticated attackers to crash the kernel by reading nonexistent MCP resources. Attackers with a valid API token can send a resources/read request in an initialized MCP session, causing a panic that terminates the kernel process and interrupts service.

Why it matters now

EPSS 0.00266 18th percentileScored 2026-11-07
Fix Fixed siyuan (siyuan-note): 3.8.9

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
siyuan-notesiyuanbefore 3.8.93.8.9Patch availableCNA
  • siyuan Vendorsiyuan-note Affected before 3.8.9 Fixed in 3.8.9 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*——siyuan-note
  • cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:* Versions — — ·siyuan-note

Remediation

Upgrade SiYuan to version 3.8.9, which fixes this flaw.

Written with Claude Haiku 5.5 from the sources below · 2026-11-08

  • Fix · CNA siyuan (siyuan-note) Fixed in 3.8.9

Timeline

  1. 2026-11-06 Threatist record created from CVE-2026-123492
  2. 2026-11-06 Alias added: GHSA-pxf5-vpcp-gg52
  3. 2026-11-08 Priority changed: MEDIUM → LOW

References

Advisory 1

  • TI-2026-48492 SiYuan before v3.7.3 SQL Injection via searchDocs CVSS 4.0CRITICAL 9.9
  • TI-2026-48491 SiYuan before v3.7.3 SQL Injection via searchEmbedBlock CVSS 4.0CRITICAL 9.9
  • TI-2026-48490 SiYuan before v3.7.3 SQL Injection via fullTextSearchAssetContent CVSS 4.0CRITICAL 9.9
  • TI-2026-47010 SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP CVSS 4.0CRITICAL 10.0
  • TI-2026-26050 SiYuan has directory traversal within its publishing service CVSS 3.1CRITICAL 9.8
  • TI-2026-25256 SiYuan: Authorization Bypass Allows Arbitrary SQL Execution via Search API CVSS 3.1CRITICAL 9.8
See all 242 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences