---
id: "CVE-2026-91985"
kind: "vulnerability"
aliases: ["CVE-2026-91985", "GHSA-qfwc-vx6f-3g6g", "GO-2026-6747"]
title: "Vikunja: Read-only project members can obtain any link share's access hash via the single-share read endpoint (v1 and v2) and escalate to the share's permission level in code.vikunja.io/api"
severity: "high"
cvss: 8.7
epss: 0.00432
exploited: false
status: "open"
category: "package"
products: [{"name": "code.vikunja.io/api", "fixed": [], "affected": "all versions", "ecosystem": "go"}, {"name": "code.vikunja.io/api", "fixed": ["2.6.0"], "affected": "<= 2.5.0 (before 2.6.0)", "ecosystem": "go"}]
ecosystems: ["go"]
tags: ["go", "link-share", "package", "privilege-escalation", "self-hosted", "vikunja"]
not_affected_if: ["managed-hosting", "no-link-shares", "no-project-link-shares", "no-read-only-members", "single-user-only"]
published_at: "2026-09-15T16:17:57+00:00"
first_seen_at: "2026-10-23T19:13:08+00:00"
updated_at: "2026-10-23T21:44:36+00:00"
sources: [{"source": "govuln", "url": "https://pkg.go.dev/vuln/GO-2026-6747", "first_seen_at": "2026-10-23T19:13:08+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91985", "first_seen_at": "2026-10-23T19:13:43+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91985", "first_seen_at": "2026-10-23T19:35:23+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T21:44:36+00:00"}]
---

# Vikunja: Read-only project members can obtain any link share's access hash via the single-share read endpoint (v1 and v2) and escalate to the share's permission level in code.vikunja.io/api

In Vikunja <= 2.5.0, any user with read-only access to a project can call GET /api/v1|v2/projects/{project}/shares/{share} and receive the link share's secret hash. They can exchange it at the unauthenticated POST /api/v1/shares/{hash}/auth for a link-share JWT at the share's permission (read-write or admin) and write to the project. Needs existing project membership and a link share on the project. Password-protected shares still need the password. Fixed in 2.6.0.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- go:code.vikunja.io/api affected all versions fixed ?
- go:code.vikunja.io/api affected <= 2.5.0 (before 2.6.0) fixed 2.6.0

## How to check

Self-hosted: check the Vikunja version (/api/v1/info or the UI footer); <= 2.5.0 is affected. Only projects that have link shares and read-only members are practically exposed. Test: as a read-only member, GET /api/v1/projects/{id}/shares/{shareId} returns 200 with a hash field if vulnerable.

## Fix

Upgrade Vikunja to 2.6.0 or later (go module code.vikunja.io/api v2.6.0). Until then, delete link shares on projects with read-only members, or rotate them after upgrading, since hashes may already be exposed.

## Timeline

- 2026-10-23T19:13:08+00:00 govuln https://pkg.go.dev/vuln/GO-2026-6747
- 2026-10-23T19:13:43+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91985
- 2026-10-23T19:35:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91985
- 2026-10-23T21:44:36+00:00 analyst — Read vendor GHSA-qfwc-vx6f-3g6g and GO-2026-6747: affected <= 2.5.0 (verified on 2.5.0, earlier likely), fixed 2.6.0. No exploitation or public-PoC beyond the advisory's own curl steps; social search not done (no CVE chatter expected). Release page v2.6.0 linked from pkg.go.dev but not read.

## Documents

- [advisory] GHSA-qfwc-vx6f-3g6g Vikunja link-share hash disclosure https://github.com/go-vikunja/vikunja/security/advisories/GHSA-qfwc-vx6f-3g6g
- [describes] GO-2026-6747 https://pkg.go.dev/vuln/GO-2026-6747
- [fix] Vikunja v2.6.0 https://github.com/go-vikunja/vikunja/releases/tag/v2.6.0

## From the sources

Vikunja: Read-only project members can obtain any link share's access hash via the single-share read endpoint (v1 and v2) and escalate to the share's permission level in code.vikunja.io/api.

NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.

(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)

The additional affected modules and versions are: code.vikunja.io/api before v2.6.0.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_