{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-40263", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-04-10T17:31:45.787Z", "datePublished": "2026-04-16T23:53:50.195Z", "dateUpdated": "2026-04-16T23:53:50.195Z"}, "containers": {"cna": {"title": "Note Mark: Username Enumeration via Login Endpoint Timing Side-Channel", "problemTypes": [{"descriptions": [{"cweId": "CWE-208", "lang": "en", "description": "CWE-208: Observable Timing Discrepancy", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 3.7, "baseSeverity": "LOW", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/enchant97/note-mark/security/advisories/GHSA-w6m9-39cv-2fwp", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/enchant97/note-mark/security/advisories/GHSA-w6m9-39cv-2fwp"}, {"name": "https://github.com/enchant97/note-mark/commit/cf4c6f6acf70b569d80396d323b067c00d45c034", "tags": ["x_refsource_MISC"], "url": "https://github.com/enchant97/note-mark/commit/cf4c6f6acf70b569d80396d323b067c00d45c034"}], "affected": [{"vendor": "enchant97", "product": "note-mark", "versions": [{"version": "< 0.19.2", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-04-16T23:53:50.195Z"}, "descriptions": [{"lang": "en", "value": "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."}], "source": {"advisory": "GHSA-w6m9-39cv-2fwp", "discovery": "UNKNOWN"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-40263", "lastModified": "2026-04-17T01:17:40.137", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 3.7, "baseSeverity": "LOW", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 1.4, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-04-17T01:17:40.137", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/enchant97/note-mark/commit/cf4c6f6acf70b569d80396d323b067c00d45c034"}, {"source": "security-advisories@github.com", "url": "https://github.com/enchant97/note-mark/security/advisories/GHSA-w6m9-39cv-2fwp"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-208"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-17T01:50:34.503389+00:00", "value": {"mitigation_remediation": ["Update Note Mark to version 0.19.2 or later", "If updating is delayed, implement a uniform response delay or dummy bcrypt processing for all login attempts to eliminate timing differences", "Apply rate limiting or CAPTCHAs on the login endpoint to reduce the feasibility of repeated timing measurements"], "summary": {"action": "Apply Patch", "impact": "User Enumeration via Timing Side-Channel"}, "threat_synthesis": {"affected_systems": "The affected product is enchant97's Note Mark. Versions 0.19.1 and older are vulnerable. The issue was fixed in version 0.19.2. No other vendors or product versions are listed.", "description_and_impact": "The vulnerability is a timing side\u2011channel in the login endpoint of the Note Mark application. When a supplied username does not exist, the system returns immediately; when the username exists, bcrypt verification is performed, causing a measurable delay. An attacker can detect this delay and enumerate valid usernames. The primary impact is disclosure of valid account names, which can then be used in targeted credential attacks. This weakness is identified as CWE-208, a timing or side\u2011channel vulnerability that compromises confidentiality of user identities.", "risk_and_exploitability": "With a CVSS score of 3.7, the vulnerability is considered low severity. The EPSS score is not available, suggesting no known public exploitation data. It is not listed in the KEV catalog. The likely attack vector is remote access to the login endpoint, where an attacker can measure response times over the network. If an attacker can reliably compare timings, they can enumerate all active usernames, facilitating credential stuffing or phishing attacks."}}}}, "created": "2026-04-17T02:00:05.863664+00:00", "updated": "2026-04-17T02:00:05.863689+00:00", "vendors": []}