Cyber Resilience

CVE-2026-23851

HighPublic PoC

Published: 19 January 2026

Published
19 January 2026
Modified
30 January 2026
KEV Added
—
Patch
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CVSS Score v4 8.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0044 34.7th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-23851 is a high-severity Path Traversal (CWE-22) vulnerability in B3Log Siyuan. Its CVSS base score is 8.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 34.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability details

SiYuan is a personal knowledge management system. Versions prior to 3.5.4 contain a logic vulnerability in the /api/file/globalCopyFiles endpoint. The function allows authenticated users to copy files from any location on the server's filesystem into the application's workspace without proper…

more

path validation. The vulnerability exists in the api/file.go source code. The function globalCopyFiles accepts a list of source paths (srcs) from the JSON request body. While the code checks if the source file exists using filelock.IsExist(src), it fails to validate whether the source path resides within the authorized workspace directory. Version 3.5.4 patches the issue.

CWE(s)
CWE-22

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Path traversal in authenticated API endpoint directly enables arbitrary local file access (T1005) on server; also facilitates exploitation of exposed application interface (T1190).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

Affected Assets

b3log
siyuan
≤ 3.5.4

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-10 Information Input Validation
addresses: CWE-22

Validates pathnames and filenames to prevent traversal outside intended directories.

References