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Vulnerability record · CVE-2026-56765 · published 10 July 2026

CVE-2026-56765: Insecure direct object reference vulnerability

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.

9.3 CVSS 4.0 Critical EPSS 0.51% · top 58.7% CWE-639 · Insecure direct object reference Deferred
9.3CVSS 4.0 base score
0.51%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
10 Jul 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j
https://www.vulncheck.com/advisories/vikunja-unauthenticated-instance-wide-data-breach-via-link-share-hash-disclosure-ch
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.4CVE-2026-55255Langflow IDOR in responses endpoint allows cross-user flow executionLangflow before 1.9.1 has an insecure direct object reference in the /api/v1/responses endpoint. An authenticated attacker can supply another user's …KEVEPSS 0.89%analysed

Source: NIST National Vulnerability Database (record CVE-2026-56765), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.