How severe is CVE-2026-23852?

CVE-2026-23852 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-23852 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-23852?

CVE-2026-23852 affects B3log Siyuan. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-23852?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-23852 have an EU (EUVD) identifier?

Yes. CVE-2026-23852 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3290.

When was CVE-2026-23852 published?

CVE-2026-23852 was published on 2026-01-19 and last updated on 2026-06-17.

CVE-2026-23852

CVE-2026-23852 is a critical-severity vulnerability in B3log Siyuan with a CVSS 3.x base score of 9.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Critical (CVSS 3.x base score 9.6)
CVSS v4: 5.8
EPSS exploit prediction: 1% (48th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-3290
Weakness: CWE-79
Affected product: B3log Siyuan
Published: 2026-01-19
Last modified: 2026-06-17

Description

SiYuan is a personal knowledge management system. Versions prior to 3.5.4 have a stored Cross-Site Scripting (XSS) vulnerability that allows an attacker to inject arbitrary HTML attributes into the `icon` attribute of a block via the `/api/attr/setBlockAttrs` API. The payload is later rendered in the dynamic icon feature in an unsanitized context, leading to stored XSS and, in the desktop environment, potential remote code execution (RCE). This issue bypasses the previous fix for issue `#15970` (XSS → RCE via dynamic icons). Version 3.5.4 contains an updated fix.

Frequently asked questions

What is CVE-2026-23852?: SiYuan is a personal knowledge management system. Versions prior to 3.5.4 have a stored Cross-Site Scripting (XSS) vulnerability that allows an attacker to inject arbitrary HTML attributes into the `icon` attribute of a block via the `/api/attr/setBlockAttrs` API. The payload is later rendered in the dynamic icon feature in an unsanitized context, leading to stored XSS and, in the desktop environment, potential remote code execution (RCE). This issue bypasses the previous fix for issue `#15970` (XSS → RCE via dynamic icons). Version 3.5.4 contains an updated fix.
How severe is CVE-2026-23852?: CVE-2026-23852 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-23852 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23852?: CVE-2026-23852 affects B3log Siyuan. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-23852?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-23852 have an EU (EUVD) identifier?: Yes. CVE-2026-23852 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3290.
When was CVE-2026-23852 published?: CVE-2026-23852 was published on 2026-01-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*

More vulnerabilities in B3log Siyuan

CVE-2026-32938 — Critical (CVSS 9.9): SiYuan is a personal knowledge management system. In versions 3.6.0 and below, the /api/lute/html2BlockDOM on the…
CVE-2026-33670 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Prior to version 3.6.2, the /api/file/readDir interface was used to…
CVE-2026-33669 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Prior to version 3.6.2, document IDs were retrieved via the…
CVE-2026-32767 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Versions 3.6.0 and below contain an authorization bypass…
CVE-2024-55660 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Prior to version 3.1.16, SiYuan's `/api/template/renderSprig`…
CVE-2024-53507 — Critical (CVSS 9.8): A SQL injection vulnerability was discovered in Siyuan 3.1.11 in /getHistoryItems.

All CVEs affecting B3log Siyuan →

Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities

CVE-2025-49410 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Imran Emu TC…
CVE-2024-47875 — Critical (CVSS 10.0): DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. DOMpurify was vulnerable to…
CVE-2024-6886 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Gitea…
CVE-2023-45144 — Critical (CVSS 10.0): com.xwiki.identity-oauth:identity-oauth-ui is a package to aid in building identity and service providers based on…
CVE-2023-45138 — Critical (CVSS 10.0): Change Request is an pplication allowing users to request changes on a wiki without publishing the changes directly.…
CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…

Browse all CWE-79 (Cross-site Scripting (XSS)) vulnerabilities →