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Authorization Bypass (IDOR)Weakness · CWE-639

CVE-2026-56765

CRITICAL · 9.8 CVSS v3.1 Published 2026-07-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Vikunja before 2.2.1 contains an authorization flaw where the LinkSharing.ReadAll endpoint exposes share hashes to users with read access, enabling permission escalation to admin-level shares. The GetTaskAttachment endpoint performs permission checks against user-supplied task IDs but fetches attachments by sequential ID without verifying ownership, allowing attackers to download and delete all file attachments across all projects instance-wide.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Vikunja before 2.2.1 has two critical authorization flaws: the LinkSharing.ReadAll endpoint exposes share hashes to read-access users, enabling privilege escalation to admin-level shares; and GetTaskAttachment performs permission checks on user-supplied task IDs but fetches attachments by sequential numeric ID without verifying ownership, allowing unauthenticated instance-wide file access and deletion.

MitigationUpgrade to Vikunja 2.2.1 or later to receive the patched authorization logic. Additionally, review access logs for suspicious enumeration of attachment IDs.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Vikunja version
    Check your running Vikunja instance version (typically via API endpoint, admin panel, or container image tag) and compare to the affected range (before 2.2.1)
    Affected if The installed version is before 2.2.1
  2. Verify LinkSharing module is active
    Confirm the LinkSharing feature is enabled in your Vikunja configuration, as the first flaw only affects environments with share links functionality
    Affected if LinkSharing is enabled and version is before 2.2.1
  3. Confirm attachment upload feature is enabled
    Verify that task attachments can be uploaded and accessed in your instance, as the second flaw requires the attachment functionality to be present
    Affected if Task attachments are enabled and version is before 2.2.1
  4. Audit share access patterns
    Review access logs for non-admin users accessing the /linksharing/readall endpoint or enumerating share hashes beyond their assigned permissions
    Affected if Read-access users accessed share hashes they should not have via the ReadAll endpoint

You are affected if running Vikunja before version 2.2.1 with LinkSharing or task attachment features enabled, and evidence exists of unauthorized share hash exposure or attachment access by low-privilege users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Vikunja 2.2.1 or later to receive the patched authorization logic. Additionally, review access logs for suspicious enumeration of attachment IDs.

Recommended fix Moderate confidence

Vikunja 2.2.1 or later

  1. 1. Identify current Vikunja installation version by checking the application or API
  2. 2. Back up the Vikunja database and all attached files before proceeding with the upgrade
  3. 3. Upgrade Vikunja to version 2.2.1 or later (the version that contains the security fix)
  4. 4. After upgrade, verify that the LinkSharing.ReadAll endpoint no longer exposes share hashes to non-admin users with read access
  5. 5. Verify that GetTaskAttachment now properly validates attachment ownership against the user's task permissions before allowing access
Caveat Review Vikunja release notes for 2.2.x series to check for any breaking changes relevant to your deployment

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA3.0 h
19.0 hours of engineering $3,380
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-56765 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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