Is CVE-2025-21609 in the CISA KEV catalog?

No. CVE-2025-21609 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-21609?

CVE-2025-21609 has a CVSS v3 base score of 9.1 (CRITICAL).

What is the EPSS score for CVE-2025-21609?

CVE-2025-21609 has an EPSS score of 0.59% (44th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2025-21609?

No published fix for CVE-2025-21609 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2025-21609

CRITICAL

9.1

CVSS v3

NVD

Description

SiYuan is self-hosted, open source personal knowledge management software. SiYuan Note version 3.1.18 has an arbitrary file deletion vulnerability. The vulnerability exists in the `POST /api/history/getDocHistoryContent` endpoint. An attacker can craft a payload to exploit this vulnerability, resulting in the deletion of arbitrary files on the server. Commit d9887aeec1b27073bec66299a9a4181dc42969f3 fixes this vulnerability and is expected to be available in version 3.1.19.

CWE-459 CWE-552

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Exploit Intelligence

0.59%probability of exploitation in 30 days

44thpercentile

Moderate risk: more likely to be exploited than 44% of all known CVEs.

References

Patch1

github.com

Exploit1

github.com

Related Vulnerabilities

Other CWE-459 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2017-17090	High	7.5	82%	-	Fix
CVE-2021-39327	Medium	5.3	72%	-	-
CVE-2025-31650	High	7.5	68%	-	Fix
CVE-2022-1552	High	8.8	12%	-	Fix
CVE-2018-18924	High	8.8	9.5%	-	-
CVE-2022-21125	Medium	5.5	6.5%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-05-14.