How severe is CVE-2026-31807?

CVE-2026-31807 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-31807 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-31807?

CVE-2026-31807 affects B3log Siyuan. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-31807?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-31807 have an EU (EUVD) identifier?

Yes. CVE-2026-31807 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10892.

When was CVE-2026-31807 published?

CVE-2026-31807 was published on 2026-03-10 and last updated on 2026-06-17.

CVE-2026-31807

CVE-2026-31807 is a medium-severity vulnerability in B3log Siyuan with a CVSS 3.x base score of 6.1. 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: Medium (CVSS 3.x base score 6.1)
CVSS v4: 6.4
EPSS exploit prediction: 0% (36th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-10892
Weakness: CWE-79
Affected product: B3log Siyuan
Published: 2026-03-10
Last modified: 2026-06-17

Description

SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) blocks dangerous elements (<script>, <iframe>, <foreignobject>) and removes on* event handlers and javascript: in href attributes. However, it does NOT block SVG animation elements (<animate>, <set>) which can dynamically set attributes to dangerous values at runtime, bypassing the static sanitization. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint (type=8), creating a reflected XSS. This is a bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in v3.5.10.

Frequently asked questions

What is CVE-2026-31807?: SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) blocks dangerous elements (<script>, <iframe>, <foreignobject>) and removes on* event handlers and javascript: in href attributes. However, it does NOT block SVG animation elements (<animate>, <set>) which can dynamically set attributes to dangerous values at runtime, bypassing the static sanitization. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint (type=8), creating a reflected XSS. This is a bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in v3.5.10.
How severe is CVE-2026-31807?: CVE-2026-31807 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-31807 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-31807?: CVE-2026-31807 affects B3log Siyuan. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-31807?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-31807 have an EU (EUVD) identifier?: Yes. CVE-2026-31807 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10892.
When was CVE-2026-31807 published?: CVE-2026-31807 was published on 2026-03-10 and last updated on 2026-06-17.

References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-5hc8-qmg8-pw27

Affected products (1)

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

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