Vulnerability · Published Apr 16, 2026 · Assigned by GitHub_M
CVE-2026-40263Note Mark: Username Enumeration via Login Endpoint Timing Side-Channel
Low 3.7
In plain English
A low-severity security flaw in note-mark from enchant97. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Note Mark is an open-source note-taking application. In versions 0.19.1 and prior, the login endpoint performs bcrypt password verification only when the supplied username exists, returning immediately for nonexistent usernames. This timing discrepancy allows unauthenticated attackers to enumerate valid usernames by measuring response times, enabling targeted credential attacks. This issue has been fixed in version 0.19.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/enchant97/note-mark/backend | 0.19.2-0.20260411145025-cf4c6f6acf70 | GHSA-w6m9-39cv-2fwp |
| Go | github.com/enchant97/note-mark/backend | no fix listed | GO-2026-5696 |
Affected products (as reported)
Weakness: CWE-208 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N