CVE-2026-34605
HighPublic exploitSiYuan vulnerable to reflected XSS via SVG namespace prefix bypass in SanitizeSVG (getDynamicIcon, unauthenticated)
Published Apr 1, 2026 · Updated Aug 12, 2026 · Also known as GHSA-73g7-86qr-jrg3, GO-2026-5201
Key Facts
Patch immediately- CVE-2026-34605 is a high-severity vulnerability (CVSS 8.6 v4) affecting Siyuan (B3log), github.com/siyuan-note/siyuan/kernel (go).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 0.6% probability of exploitation in the next 30 days.
- Fixed versions are available, including Siyuan 3.6.2, github.com/siyuan-note/siyuan/kernel 0.0.0-20260330031106-f09953afc57a.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
CVSS v4
8.6
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/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 (30-day exploit likelihood)
0.6%
Higher than 47.7% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-34605 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
SiYuan is a personal knowledge management system. From version 3.6.0 to before version 3.6.2, the SanitizeSVG function introduced in version 3.6.0 to fix XSS in the unauthenticated /api/icon/getDynamicIcon endpoint can be bypassed by using namespace-prefixed element names such as . The Go HTML5 parser records the element's tag as "x:script" rather than "script", so the tag check passes it through. The SVG is served with Content-Type: image/svg+xml and no Content Security Policy; when a browser opens the response directly, its XML parser resolves the prefix to the SVG namespace and executes the embedded script. This issue has been patched in version 3.6.2.
Affected Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| SiyuanB3log | >= >= 3.6.0, < 3.6.2 | 3.6.2 |
| github.com/siyuan-note/siyuan/kernelgo | See advisory | 0.0.0-20260330031106-f09953afc57a |
Patched Releases
Siyuan
3.6.2
github.com/siyuan-note/siyuan/kernel
0.0.0-20260330031106-f09953afc57a
Timeline
Publicly disclosed
Apr 1, 2026
Last updated
Aug 12, 2026
Weakness Type
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
References
- advisoryGHSA advisory
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34605.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-34605
- articlehttps://github.com/siyuan-note/siyuan/issues/17246
- articlehttps://github.com/siyuan-note/siyuan/releases/tag/v3.6.2
FAQ
Common Questions.
SiYuan is a personal knowledge management system.
Affected: Siyuan (B3log) versions >= >= 3.6.0, < 3.6.2; github.com/siyuan-note/siyuan/kernel (go). The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Siyuan 3.6.2, github.com/siyuan-note/siyuan/kernel 0.0.0-20260330031106-f09953afc57a.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
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