cve.bz

CVE-2026-31809

6.4 mediumEPSS 0.5%

Medium (6.4) in b3log siyuan. EPSS 0.5% chance of exploitation in the next 30 days. Fixed in github.com/siyuan-note/siyuan/kernel 0.0.0-20260310025236-297bd526708f.

SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) checks href attributes for the javascript: prefix using strings.HasPrefix(). However, inserting ASCII tab (	), newline (
), or carriage return (
) characters inside the javascript: string bypasses this prefix check. Browsers strip these characters per the WHATWG URL specification before parsing the URL scheme, so the JavaScript still executes. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint, creating a reflected XSS. This is a second bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in 3.5.10.

Severity

CVSS 4.0

6.4 medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

CVSS 3.1

6.1 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS
0.5% chance of exploitation in the next 30 days; higher than 43% of CVEs (scores of 2026-10-31)
CWE
CWE-79
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-pmc9-f5qr-2pcrGogithub.com/siyuan-note/siyuan/kernel<0.0.0-20260310025236-297bd526708f0.0.0-20260310025236-297bd526708f
GO-2026-4669Gogithub.com/siyuan-note/siyuan/kernel<0.0.0-20260310025236-297bd526708f0.0.0-20260310025236-297bd526708f

References

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