CVE-2026-35597
Vikunja ≤ 2.3.0
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:NSummary
CVE-2026-35597 is a medium-severity Improper Restriction of Excessive Authentication Attempts (CWE-307) vulnerability in Vikunja Vikunja. Its CVSS base score is 5.9 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 22th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-7 (Unsuccessful Logon Attempts) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-35597 affects Vikunja, an open-source self-hosted task management platform, in versions prior to 2.3.0. The vulnerability stems from a database transaction handling bug that renders the TOTP failed-attempt lockout mechanism non-functional. Specifically, when TOTP validation fails, the login handler in pkg/routes/api/v1/login.go calls HandleFailedTOTPAuth in pkg/user/totp.go, which increments an in-memory counter and attempts to set the user status to locked after 10 failures using the same database session. However, the login handler unconditionally rolls back the transaction afterward, undoing the lockout write while the counter continues to increment, allowing unlimited brute-force attempts against TOTP codes. The issue is rated 5.9 on CVSS 3.1 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N) and maps to CWE-307 (Improper Restriction of Excessive Authentication Attempts).
Unauthenticated remote attackers can exploit this vulnerability over the network with high attack complexity and no user interaction required. By repeatedly submitting invalid TOTP codes, attackers bypass the intended lockout, enabling brute-force attacks to guess valid TOTP codes and gain unauthorized access to user accounts, resulting in high confidentiality impact through potential exposure of sensitive task management data.
Vikunja addresses this vulnerability in version 2.3.0, as detailed in the GitHub security advisory GHSA-fgfv-pv97-6cmj, the associated pull request #2576, and the release notes. The fix is implemented via commit 6ca0151d02fa0e8c7e2181ab916a28e08caaaec8, which resolves the transaction rollback issue to properly enforce TOTP lockouts. Security practitioners should upgrade to 2.3.0 or later to mitigate the risk.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-21422
Vulnerability Data
Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the TOTP failed-attempt lockout mechanism is non-functional due to a database transaction handling bug. When a TOTP validation fails, the login handler in pkg/routes/api/v1/login.go calls HandleFailedTOTPAuth and then unconditionally…
more
rolls back. HandleFailedTOTPAuth in pkg/user/totp.go uses an in-memory counter (key-value store) to track failed attempts. When the counter reaches 10, it calls user.SetStatus(s, StatusAccountLocked) on the same database session s. Because the login handler always rolls back after a TOTP failure, the StatusAccountLocked write is undone. The in-memory counter correctly increments past 10, so the lockout code executes on every subsequent attempt, but the database write is rolled back every time. This allows unlimited brute-force attempts against TOTP codes. This vulnerability is fixed in 2.3.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 2 hardening rules · 1 OS baseline
—
Mitigating Controls (NIST 800-53 r5) AI
AC-7 directly enforces limits on consecutive failed logons, structurally blocking brute-force exploitation of the weakness.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Authentication enforcement directly includes lockout, throttling, and MFA policies that prevent brute-force attempts.
Behavioral monitoring of authentication activity can detect excessive failed attempts after they occur.
Generating auth logs enables later detection or forensics but does not itself restrict attempts.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
CAPTCHA, account lock-out after repeated failures, and alerts on excessive attempts directly stop automated brute-force guessing of credentials.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
RHEL 7 (2 rules)
- V-204427 The Red Hat Enterprise Linux operating system must be configured to lock accounts for a minimum of 15 minutes after three unsuccessful logon attempts within a 15-minute timeframe. prevents CWE-307
- V-204428 The Red Hat Enterprise Linux operating system must lock the associated account after three unsuccessful root logon attempts are made within a 15-minute period. prevents CWE-307