Note Mark: Username Enumeration via Login Endpoint Timing Side-Channel
Priority MEDIUM 51CWE-208Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-208.
Summary
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00258 17th percentileScored 2026-11-07
Fix Fixed note-mark (enchant97): 0.19.2github.com/enchant97/note-mark/backend (Go): 0.19.2-0.20260411145025-cf4c6f6acf70
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| enchant97 | note-mark | before 0.19.2 | 0.19.2 | Patch available | CNA |
| — | github.com/enchant97/note-mark/backend (Go) | before 0.19.2-0.20260411145025-cf4c6f6acf70 | 0.19.2-0.20260411145025-cf4c6f6acf70 | Patch available | GHSA-w6m9-39cv-2fwp |
- note-mark Vendorenchant97 Affected before 0.19.2 Fixed in 0.19.2 Patch available CNA
- github.com/enchant97/note-mark/backend (Go) Vendor— Affected before 0.19.2-0.20260411145025-cf4c6f6acf70 Fixed in 0.19.2-0.20260411145025-cf4c6f6acf70 Patch available GHSA-w6m9-39cv-2fwp
Remediation
- Fix · CNA note-mark (enchant97) Fixed in 0.19.2
- Fix · GHSA-w6m9-39cv-2fwp github.com/enchant97/note-mark/backend (Go) Fixed in 0.19.2-0.20260411145025-cf4c6f6acf70 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-40263
- 2026-10-03 Alias added: GHSA-w6m9-39cv-2fwp
References
More enchant97 vulnerabilities
- TI-2026-32452 Note Mark: JWT Secret Weakness allows Full Account Takeover via token forgery CVSS 3.1CRITICAL 10.0
- TI-2026-30126 Note Mark: OIDC-registered users authenticated by submitting password "null" CVSS 3.1CRITICAL 9.4
- TI-2026-29056 Note Mark has Stored XSS via Unrestricted Asset Upload CVSS 3.1HIGH 8.7
- TI-2026-37275 Note Mark: Path traversal via unsanitized book/note slug in migrate export (sibling of GHSA-g49p) CVSS 4.0HIGH 8.6
- TI-2026-32451 Note Mark: Arbitrary File Write via Path Traversal in Asset Names Leading to Remote Code Execution CVSS 4.0HIGH 8.6
- TI-2026-37276 Note Mark: Unauthenticated disclosure of soft-deleted note metadata via deleted=true on public books in note-mark CVSS 3.1MEDIUM 5.3
Sources
- CVE-2026-40263 · CVE Program
- CVE-2026-40263 · NVD
- FIRST EPSS
- GHSA-w6m9-39cv-2fwp · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences