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CVE-2026-82653

CRITICAL 9.3 PoC AVAILABLE

Published 2026-08-30 · Last modified 2026-09-02

SiYuan before v3.8.1 contains a stored cross-site scripting vulnerability in confirmDialog() where unescaped package names and notebook names are interpolated directly into innerHTML assignments. Attackers can submit malicious bazaar packages with HTML/script payloads in the name field that execute in users' browsers when uninstalling packages or unlocking encrypted notebooks.

EXPLOIT AVAILABLE

Public exploit or PoC code exists. Modeled probability is still low, but the barrier to attack is reduced — watch closely.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 13th percentile

○ In CISA KEV ● Public exploit / PoC

Impact if exploited

9.3CVSS 4.0 · CRITICAL

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityLow

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ⚠User interaction: Succeeds with passive user activity
  • ✓Complexity: No special conditions — reliably repeatable
  • ✓Requirements: No special attack requirements

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-82653/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-82653/poc.json

Affected

Vendors Siyuan Note

Products Siyuan

Weakness (CWE)

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

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

All CVSS metrics

  • CRITICAL 9.3 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
  • HIGH 8.9 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L
  • CRITICAL 9.3 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/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
  • HIGH 8.9 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L

References

Exploits & PoC

Advisories

Sources: NVD · CVE.org · EPSS