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Vikunja CVE-2026-33676

| EUVDEUVD-2026-14917 MEDIUM
Incorrect Authorization (CWE-863)
2026-03-24 GitHub_M GHSA-8cmm-j6c4-rr8v
6.5
CVSS 3.1 · GitHub Advisory
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization logic validation
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

The CVSS 6.5 score reflects a medium-to-high information disclosure risk with attack vector network, low attack complexity, and low privilege requirements (authenticated user needed). The vulnerability requires valid authentication credentials and knowledge of task identifiers with cross-project relationships, reducing opportunistic exploitation likelihood. No public exploit code or proof-of-concept has been referenced in available sources, and the vulnerability does not appear in known exploit databases (KEV status unclear from provided data). However, the technical impact is significant for multi-tenant or sensitive environments where task segregation is a security boundary. The automatable nature of API enumeration means that once a foothold is established, systematic information harvesting of cross-referenced tasks becomes trivial. For organizations using Vikunja in security-sensitive contexts (e.g., managing confidential project workflows), this warrants rapid patching despite the moderate CVSS score, as information disclosure can enable privilege escalation or social engineering attacks. For casual self-hosted instances, the risk is lower but still material.

Exploit ScenarioDerived

An authenticated user (such as a contractor with access to one project) discovers via the UI that their assigned task has a cross-project relation to another task. They intercept the API response or construct a direct API request to retrieve that task object and receive the full details including the related task's title, description, due date, and project ID from a restricted project. The attacker then uses this metadata to infer sensitive business information (e.g., upcoming product launches, organizational changes) or social engineer colleagues for further access. Since the attack requires only authentication and knowledge of existing task relationships, any user with valid credentials can execute this exploitation path with minimal technical complexity.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 24, 2026

Vikunja prior to version 2.2.1 suffers from an information disclosure vulnerability where the API returns full task object details in the related_tasks field without validating the requesting user's read permissions on the related tasks' projects. An authenticated attacker can exploit cross-project task relationships to enumerate sensitive task metadata (titles, descriptions, due dates, priorities, completion percentages, project IDs) from projects they have no access to, achieving a high-confidence information disclosure with CVSS 6.5 and no active exploitation reported in known exploit databases.

RemediationAI

Upgrade Vikunja to version 2.2.1 or later immediately. The patch is available via the official GitHub repository at https://github.com/go-vikunja/vikunja/pull/2449 and the implementing commit 833f2aec006ac0f6643c41872e45dd79220b9174. For deployments unable to patch immediately, restrict API access to trusted network ranges using firewall rules or a reverse proxy, enforce mutual TLS authentication if applicable, and audit API access logs for suspicious enumeration patterns (repeated requests to related_tasks fields across multiple task IDs). Consider temporarily disabling cross-project task linking features at the application configuration level if the risk profile is particularly high.

Affected VersionsENISA

vikunja < 2.2.1

Affected Packages

go code.vikunja.io/api fix: 2.2.1
euvd vikunja fix: 2.2.1

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in go, euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability stems from insufficient access control checks (CWE-863: Incorrect Authorization) in Vikunja's task relationship handling logic. Vikunja is a self-hosted task management platform that supports cross-project task relations via a related_tasks field. The affected product line is identified by CPE cpe:2.3:a:go-vikunja:vikunja:*:*:*:*:*:*:*:* with versions prior to 2.2.1. When the API endpoint returns task objects, the serialization process populates related task references with complete task data structures without first performing authorization checks to confirm the requesting user has read access to the project containing each related task. This is a classic case of authorization bypass in REST API response filtering where child/related objects inherit visibility rules from the parent rather than enforcing independent permission checks.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
SUSE MEDIUM

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Mar 24, 2026 - 15:35 nvd
MEDIUM 6.5

DescriptionGitHub Advisory

Vikunja is an open-source self-hosted task management platform. Prior to version 2.2.1, when the Vikunja API returns tasks, it populates the related_tasks field with full task objects for all related tasks without checking whether the requesting user has read permission on those tasks' projects. An authenticated user who can read a task that has cross-project relations will receive full details (title, description, due dates, priority, percent completion, project ID, etc.) of tasks in projects they have no access to. Version 2.2.1 patches the issue.

Executive ViewAI

Why It Matters

Organizations using Vikunja should be aware of notable risk from CVE-2026-33676, a incorrect authorization vulnerability rated CVSS 6.5. Attackers could gain access beyond their authorized level. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Moderate
Compensating Controls

Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.

Threat Intelligence Overview

EPSS Score
0.0%
Top 92% exploitable
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment Vendor GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

Exploitation
Poc
System Exposure· derived
Open
Automatable
No
Technical Impact
Partial

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

CVE-2026-68582 CRITICAL POC
9.3 Aug 02

Cross-tenant information disclosure in the self-hosted task manager Vikunja (0.24.0 through 2.3.0) lets a holder of any

CVE-2026-27575 CRITICAL POC
9.1 Feb 25

Weak password policy in Vikunja task management before 2.0.0 allows users to set trivially guessable passwords. PoC avai

CVE-2026-68581 HIGH POC
8.6 Aug 02

Principal type confusion in Vikunja (versions 0.22.0-2.3.0) allows an authenticated low-privilege attacker to fully cont

CVE-2026-27616 HIGH POC
7.3 Feb 25

Stored cross-site scripting (XSS) in Vikunja prior to version 2.0.0 allows authenticated attackers to steal authenticati

CVE-2026-27819 HIGH POC
7.2 Feb 25

Vikunja before version 2.0.0 contains a path traversal vulnerability in its backup restoration function that fails to va

CVE-2026-27116 MEDIUM POC
6.1 Feb 25

Vikunja is an open-source self-hosted task management platform. [CVSS 6.1 MEDIUM]

CVE-2026-28268 CRITICAL
9.8 Feb 27

Business logic vulnerability in Vikunja task management platform before 2.1.0 allows incomplete resource cleanup, potent

CVE-2026-56765 CRITICAL
9.3 Jul 10

Instance-wide data breach in Vikunja before 2.2.1 lets remote attackers exfiltrate and destroy every file attachment acr

CVE-2026-34727 CRITICAL
9.1 Apr 10

Vikunja's OIDC callback handler issues a full JWT to any successfully matched user without checking whether that account

CVE-2026-91973 HIGH POC
8.7 Sep 15

Vikunja instances before 2.6.0 expose CalDAV BasicAuth endpoints (/dav, /.well-known, and /feeds) that are not covered b

CVE-2026-91972 HIGH POC
8.7 Sep 15

Vikunja versions before 2.6.0 ship authentication endpoints under /api/v2 (login, register, password-reset, and OAuth to

CVE-2026-91985 HIGH POC
8.7 Sep 15

Vikunja prior to 2.6.0 leaks the secret hash that backs a project's link shares through its single-share read endpoint,

Vendor StatusVendor

SUSE

Severity: Medium
Product Status
openSUSE Leap 15.6 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP5 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP6 Fixed
openSUSE Leap 15.5 Fixed

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