MEDIUM CVSS 5.4
Published: 2026-04-01

CVE-2026-33978

streetwriters notesnook_mobile Security Advisory (CVE-2026-33978)
↗ Official NIST NVD Record
Seeking technical exploit breakdowns or verified PoC code for CVE-2026-33978?
🔬 Search Writeups & Exploit Archive →

CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-33978 impacting streetwriters notesnook_mobile. Evaluated with CVSS Base Score of 5.4 (MEDIUM).

Original NVD Description

Source: NIST NVD
Notesnook is a note-taking app focused on user privacy & ease of use. Prior to version 3.3.17, a stored XSS vulnerability exists in the mobile share / web clip flow because attacker-controlled clip metadata is concatenated into HTML without escaping and then rendered with innerHTML inside the mobile share editor WebView. An attacker can control the shared title metadata (for example through Android/iOS share metadata such as TITLE / SUBJECT, or through link-preview title data) and inject HTML such as </a><img src=x onerror=...>. When the victim opens the Notesnook share flow and selects Web clip, the payload is inserted into the generated HTML and executed in the mobile editor WebView. This issue has been patched in version 3.3.17.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
Required (UI:R)
User must click or open resource
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product streetwriters / notesnook_mobile
Affected Versions *
Weakness Enumeration CWE-79

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-33978 impacting streetwriters notesnook_mobile.

⚡ Nuclei Detection Template (YAML) cve-2026-33978.yaml
id: cve-2026-33978

info:
  name: streetwriters notesnook_mobile - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-33978 affecting streetwriters notesnook_mobile.
    Evaluation: Notesnook is a note-taking app focused on user privacy &amp; ease of use. Prior to version 3.3.17, a stored XSS vulnerability exists in the mobile sha...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-33978
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
    cvss-score: 5.4
    cve-id: CVE-2026-33978
    cwe-id: CWE-79
  tags: cve,cve-2026-33978,streetwriters,notesnook_mobile,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "notesnook_mobile"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-33978.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-33978
# Target: streetwriters notesnook_mobile | CVSS: 5.4 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-33978 (streetwriters notesnook_mobile)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against streetwriters notesnook_mobile scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-33978.sh
# Recommended Remediation & Patching Commands for CVE-2026-33978
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install notesnook_mobile 2>/dev/null || \
sudo dnf upgrade notesnook_mobile 2>/dev/null || \
sudo yum update notesnook_mobile

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i notesnook_mobile 2>/dev/null || rpm -qa | grep -i notesnook_mobile

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-33978 in streetwriters notesnook_mobile?

Review vendor-specific security notices and update streetwriters notesnook_mobile packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-33978?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-33978?

CVE-2026-33978 is classified with a CVSS 3.1 Base Score of 5.4 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.4
MEDIUM SEVERITY
CVE ID CVE-2026-33978
Weakness CWE-79
Vendor streetwriters
Product notesnook_mobile
Published 2026-04-01
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N