CVE-2026-40262

8.7 HIGH 0.3% exploit odds Fix listed XSS

What it is

Note Mark is an open-source note-taking application. In versions 0.19.1 and prior, the asset delivery handler serves uploaded files inline and relies on magic-byte detection for content type, which does not identify text-based formats such as HTML, SVG, or XHTML. These files are served with an empty Content-Type, no X-Content-Type-Options: nosniff header, and inline disposition, allowing browsers to sniff and render active content. An authenticated user can upload an HTML or SVG file containing JavaScript as a note asset, and when a victim navigates to the asset URL, the script executes under the application's origin with access to the victim's authenticated session and API actions. This issue has been fixed in version 0.19.2.

At a glance

Exploitability: Can be exploited over the network with a low-privilege account, but needs a user to act. High risk of data exposure, data tampering.
Exploit odds: 0.3% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-04-17 01:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-26 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.3% in the next 30 days (EPSS).
Severity: 8.7 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-04-17 01:17 UTC
Last modified: 2026-10-26 21:10 UTC
Exploit probability: 0.3% · EPSS, next 30 days
Weakness: CWE-79 · Cross-site scripting
Record status: Deferred

Attack profile CVSS 3.1 · 8.7

Attack vector: Network
Complexity: Low
Privileges needed: Low
User interaction: Required
Scope: Changed
Confidentiality: High
Integrity: High
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-40262.md and follow it. Check whether this project is affected by CVE-2026-40262. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record