Description
SiYuan versions before v3.7.4 contain a missing authorization vulnerability in the /api/ref/refreshBacklink endpoint that allows anonymous readers to trigger persistent server-side writes. Attackers can invoke the endpoint with an attacker-controlled block ID to flush transaction queues, scan all references globally, and enqueue database writes, bypassing read-only protections and enabling resource amplification attacks.
Published: 2026-08-14
Score: 6.9 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

SiYuan versions before 3.7.4 contain an authorization flaw in the /api/ref/refreshBacklink endpoint. The flaw allows any anonymous user to invoke the endpoint with a supplied block ID, causing the server to perform persistent writes. This bypasses read‑only protections and can be used for resource amplification attacks, potentially leading to unauthorized data modification and exhaustion of server resources.

Affected Systems

Siyuan (siyuan-note:siyuan) – all releases prior to version 3.7.4 are affected. No further sub‑version details are provided.

Risk and Exploitability

The CVSS score is 6.9, indicating a moderate severity. The EPSS score is not available, so the current exploitation probability cannot be quantified. The vulnerability is not listed in the CISA KEV catalog. Attackers can exploit it by sending unauthenticated requests to the endpoint, thereby triggering server‑side writes and enabling resource‑amplification attacks.

Generated by OpenCVE AI on August 14, 2026 at 12:29 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update Siyuan to version 3.7.4 or later, which contains the authorization fix for refreshBacklink.
  • Re‑configure the application to restrict /api/ref/refreshBacklink to authenticated users only, ensuring the endpoint cannot be accessed anonymously.
  • Monitor inbound traffic for unusual usage of refreshBacklink and apply rate‑limiting or firewall rules to mitigate potential abuse until a permanent fix is applied.

Generated by OpenCVE AI on August 14, 2026 at 12:29 UTC.

Tracking

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Advisories

No advisories yet.

History

Wed, 19 Aug 2026 02:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Fri, 14 Aug 2026 17:15:00 +0000

Type Values Removed Values Added
First Time appeared B3log
B3log siyuan
CPEs cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*
Vendors & Products B3log
B3log siyuan

Fri, 14 Aug 2026 14:00:00 +0000

Type Values Removed Values Added
First Time appeared Siyuan
Siyuan siyuan
Vendors & Products Siyuan
Siyuan siyuan

Fri, 14 Aug 2026 11:45:00 +0000

Type Values Removed Values Added
Description SiYuan versions before v3.7.4 contain a missing authorization vulnerability in the /api/ref/refreshBacklink endpoint that allows anonymous readers to trigger persistent server-side writes. Attackers can invoke the endpoint with an attacker-controlled block ID to flush transaction queues, scan all references globally, and enqueue database writes, bypassing read-only protections and enabling resource amplification attacks.
Title SiYuan before v3.7.4 Missing Authorization via refreshBacklink
Weaknesses CWE-862
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N'}

Subscriptions

B3log Siyuan
Siyuan Siyuan
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-17T16:09:23.114Z

Reserved: 2026-08-10T15:12:16.753Z

Link: CVE-2026-72812

cve-icon Vulnrichment

Updated: 2026-08-17T15:44:59.022Z

cve-icon NVD

Status : Deferred

Published: 2026-08-14T12:16:44.063

Modified: 2026-08-26T16:57:52.167

Link: CVE-2026-72812

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-14T13:45:16Z

Weaknesses