CVE-2026-91985: Vikunja before 2.6.0 Privilege Escalation via Link Share Hash

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-15 · updated 2026-09-16
Weakness: CWE-200

Description

Vikunja before 2.6.0 fails to properly restrict access to the link-share hash field in single-share read endpoints, allowing read-only members to obtain the share's secret credential. Attackers can exchange the disclosed hash for a link-share JWT at the share's permission level to escalate privileges and perform unauthorized writes or administrative actions.

Affected products

go-vikunja vikunja: before 2.6.0 — fixed in 2.6.0

How to fix

Upgrade to a fixed version: go-vikunja vikunja 2.6.0. Check the vendor advisory for mitigations.

References

https://github.com/go-vikunja/vikunja/security/advisories/GHSA-qfwc-vx6f-3g6g
https://www.vulncheck.com/advisories/vikunja-before-2.6.0-privilege-escalation-via-link-share-hash
https://github.com/go-vikunja/vikunja/security/advisories/GHSA-qfwc-vx6f-3g6g

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