How severe is CVE-2026-40263?

CVE-2026-40263 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-40263 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40263?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-40263 have an EU (EUVD) identifier?

Yes. CVE-2026-40263 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23334.

When was CVE-2026-40263 published?

CVE-2026-40263 was published on 2026-04-17 and last updated on 2026-06-17.

CVE-2026-40263

CVE-2026-40263 is a low-severity vulnerability with a CVSS 3.x base score of 3.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-208.

Key facts

Severity: Low (CVSS 3.x base score 3.7)
EPSS exploit prediction: 0% (10th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23334
Weakness: CWE-208
Published: 2026-04-17
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-40263?: 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.
How severe is CVE-2026-40263?: CVE-2026-40263 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-40263 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-40263?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-40263 have an EU (EUVD) identifier?: Yes. CVE-2026-40263 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23334.
When was CVE-2026-40263 published?: CVE-2026-40263 was published on 2026-04-17 and last updated on 2026-06-17.

References

Other CWE-208 vulnerabilities

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