Vikunja has TOTP Two-Factor Authentication Bypass via OIDC Login Path

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.4 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

• CVE-2026-34727: 0.28% estimated exploitation activity in the next 30 days; percentile 20.66 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The OIDC callback handler issues a full JWT token without checking whether the matched user has TOTP two-factor authentication enabled. When a local user with TOTP enrolled is matched via the OIDC email fallback mechanism, the second factor is completely skipped. Details The OIDC callback at pkg/modules/auth/openid/openid.go:185 issues a JWT directly after user lookup: There are zero references to TOTP in the entire pkg/modules/auth/openid/ directory. By contrast, the local login handler at pkg/routes/api/v1/login.go:79-102 correctly implements TOTP verification: When OIDC EmailFallback maps to a local user who has TOTP enabled, the TOTP enrollment is ignored and a full JWT is issued without any second-factor challenge. Proof of Concept Tested on Vikunja v2.2.2 with Dex as the OIDC provider. Setup: - Vikunja configured with emailfallback: true for Dex - Local user alice (id=1) has TOTP enabled Output: Local login correctly requires TOTP (412), but the OIDC path issued a JWT…

Published by the source

10 Apr 2026, 15:30 UTC

Last modified by the source

10 Apr 2026, 19:35 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8jvc-mcx6-r4cg

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# Patch Next advisory brief: CVE-2026-34727

Advisory: Vikunja has TOTP Two-Factor Authentication Bypass via OIDC Login Path
IDs: CVE-2026-34727, GHSA-8jvc-mcx6-r4cg
Record: https://patchnext.com/advisories/cve-2026-34727 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: code.vikunja.io/api 2.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go code.vikunja.io/api: affected <= 2.2.2; fixed in 2.3.0

## Suggested inspection (read-only)
- Go code.vikunja.io/api: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on code.vikunja.io/api.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8jvc-mcx6-r4cg (GitHub-reviewed advisory GHSA-8jvc-mcx6-r4cg lists affected ranges: Go code.vikunja.io/api >=0 <=2.2.2)

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