CVE-2026-56765 | Vikunja before 2.2.1 contains an authorization flaw where th… | CVSS 9.8 CRITICAL

Description

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.

Metadata

CVE ID: CVE-2026-56765
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-06-22 21:55 UTC
Published: 2026-07-10 13:57 UTC
Last updated: 2026-07-10 17:00 UTC
Primary CWE: CWE-639
Authorization Bypass Through User-Controlled Key
Vendor / Product: Vikunja / Vikunja
Sources: cve.org · NVD

Severity & Metrics

9.8 CRITICAL CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: PoC
Automatable: yes
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
Vikunja	Vikunja	—	0 < 2.2.1, 2.2.1

Weakness (CWE)

CWE	Source	Description
CWE-639	cna	Authorization Bypass Through User-Controlled Key

CVSS scores (2)

Score	Severity	Version	Source	Vector
9.8	CRITICAL	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3	CRITICAL	4.0	cna	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References (2)

GitHub Security Advisory (GHSA-2pv8-4c52-mf8j) https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j
VulnCheck Advisory: Vikunja - Unauthenticated Instance-Wide Data Breach via Link Share Hash Disclosure Chained with Cross-Project Attachment IDOR https://www.vulncheck.com/advisories/vikunja-unauthenticated-instance-wide-data-breach-via-link-share-hash-disclosure-chained-with-cross-project-attachment-idor