CVE-2026-91983

Vikunja before 2.6.0 API Token Scope Bypass via expand Parameter

MEDIUM
4.3
CVSS Score
Published: September 15, 2026 at 03:18 PM UTC
Updated: September 16, 2026 at 08:34 PM UTC
1 product affected across 1 vendorVikunja

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.3%
SSVC
PoC

Description

Vikunja before 2.6.0 contains an API token scope bypass vulnerability in task read endpoints where authorization fails to inspect query string parameters. Attackers with limited token scopes can use the expand parameter to access restricted data like comments, reactions, and time entries without proper permission verification.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

1.0.0 ≤ v < 2.6.01.0.0
Vendor states this is fixed in 2.6.0 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-863

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