Is CVE-2026-40263 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-40263 being exploited in the wild.

How severe is CVE-2026-40263?

Low severity, with a CVSS score of 3.7, published 17 April 2026.

Which products and versions are affected?

github.com/enchant97/note-mark/backend (Go) < 0.19.2-0.20260411145025-cf4c6f6acf70, SEMVER:introduced=0, SEMVER:introduced=0,fixed=0.19.2-0.20260411145025-cf4c6f6acf70.

Is there a fix for CVE-2026-40263?

Yes. github.com/enchant97/note-mark/backend (Go): upgrade to 0.19.2-0.20260411145025-cf4c6f6acf70 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Am I affected by CVE-2026-40263?

Check whether you run github.com/enchant97/note-mark/backend (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40263: Note Mark: Username Enumeration via Login Endpoint Timing Side-Channel

Q: Is there a fix for CVE-2026-40263?

Yes. github.com/enchant97/note-mark/backend (Go): upgrade to 0.19.2-0.20260411145025-cf4c6f6acf70 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: Am I affected by CVE-2026-40263?

Check whether you run github.com/enchant97/note-mark/backend (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40263 · Severity: low · CVSS 3.7 · Published 2026-04-17

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.

Technologies: github.com/enchant97/note-mark/backend (Go). Vendors: Go.

Quick answers

Is CVE-2026-40263 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-40263 being exploited in the wild.
How severe is CVE-2026-40263?: Low severity, with a CVSS score of 3.7, published 17 April 2026.
Which products and versions are affected?: github.com/enchant97/note-mark/backend (Go) < 0.19.2-0.20260411145025-cf4c6f6acf70, SEMVER:introduced=0, SEMVER:introduced=0,fixed=0.19.2-0.20260411145025-cf4c6f6acf70.
Is there a fix for CVE-2026-40263?: Yes. github.com/enchant97/note-mark/backend (Go): upgrade to 0.19.2-0.20260411145025-cf4c6f6acf70 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-40263?: Check whether you run github.com/enchant97/note-mark/backend (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

github.com/enchant97/note-mark/backend (Go): upgrade to 0.19.2-0.20260411145025-cf4c6f6acf70 or later
```
go get github.com/enchant97/note-mark/backend@v0.19.2-0.20260411145025-cf4c6f6acf70
```

Affected products

github.com/enchant97/note-mark/backend (Go) < 0.19.2-0.20260411145025-cf4c6f6acf70, SEMVER:introduced=0, SEMVER:introduced=0,fixed=0.19.2-0.20260411145025-cf4c6f6acf70

Identifiers

CVE-2026-40263
GHSA-w6m9-39cv-2fwp
GO-2026-5696

References

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