CVE-2026-40103

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's scoped API token enforcement for custom project background routes is method-confused. A token with only projects.background can successfully delete a project background, while a token with only projects.background_delete is rejected. This is a scoped-token authorization bypass. This vulnerability is fixed in 2.3.0.

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's scoped API token enforcement for custom project background routes is method-confused. A token with only projects.background can successfully delete a project background, while a token with only projects.background_delete is rejected. This is a scoped-token authorization bypass. This vulnerability is fixed in 2.3.0.

Summary

Vikunja's scoped API token enforcement for custom project background routes is method-confused. A token with only projects.background can successfully delete a project background, while a token with only projects.background_delete is rejected.

This is a scoped-token authorization bypass.

Details

I verified this locally on commit c5450fb55f5192508638cbb3a6956438452a712e.

Relevant code paths:

• pkg/models/api_routes.go
• pkg/routes/routes.go
• pkg/modules/background/handler/background.go

Route registration exposes separate permissions for the same path:

• GET /api/v1/projects/:project/background -> projects.background
• DELETE /api/v1/projects/:project/background -> projects.background_delete

At enforcement time, CanDoAPIRoute() falls back to the parent group and reconstructs the child permission from the path segments only. For the DELETE request, that becomes background, so the matcher accepts any token containing projects.background without re-checking the HTTP method or matching the stored route detail.

This matters because RemoveProjectBackground() is a real destructive operation:

• It checks project update rights.
• It deletes the background file if present.
• It clears the project's BackgroundFileID.

PoC

1. Log in as a user who can update a project that already has a background.
2. Create an API token with only: {"projects":["background"]}
3. Send: DELETE /api/v1/projects/<project_id>/background Authorization: Bearer <token>
4. Observe that the request succeeds and the project background is removed.

For comparison:

1. Create an API token with only: {"projects":["background_delete"]}
2. Repeat the same DELETE request.
3. Observe that the request is rejected with 401 Unauthorized.

I confirmed this locally with three validations:

1. /api/v1/routes advertises both background and background_delete.
2. The matcher unit test proves CanDoAPIRoute() accepts DELETE for background.
3. The webtest proves a real API token with only background successfully deletes the background.

Impact

Scoped API tokens can exceed their intended capability. A token intended for project background access can delete project backgrounds, which weakens the trust model for automation and third-party integrations that rely on narrowly scoped tokens.

The attacker needs a valid API token created by a user who has update rights on the target project, but the token itself only needs the weaker projects.background permission.

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's scoped API token enforcement for custom project background routes is method-confused. A token with only projects.background can successfully delete a project background, while a token with only projects.background_delete is rejected. This is a scoped-token authorization bypass. This vulnerability is fixed in 2.3.0.

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's scoped API token enforcement for custom project background routes is method-confused. A token with only projects.background can successfully delete a project background, while a token with only projects.background_delete is rejected. This is a scoped-token authorization bypass. This vulnerability is fixed in 2.3.0.

Summary

Vikunja's scoped API token enforcement for custom project background routes is method-confused. A token with only projects.background can successfully delete a project background, while a token with only projects.background_delete is rejected.

This is a scoped-token authorization bypass.

Details

I verified this locally on commit c5450fb55f5192508638cbb3a6956438452a712e.

Relevant code paths:

• pkg/models/api_routes.go
• pkg/routes/routes.go
• pkg/modules/background/handler/background.go

Route registration exposes separate permissions for the same path:

• GET /api/v1/projects/:project/background -> projects.background
• DELETE /api/v1/projects/:project/background -> projects.background_delete

At enforcement time, CanDoAPIRoute() falls back to the parent group and reconstructs the child permission from the path segments only. For the DELETE request, that becomes background, so the matcher accepts any token containing projects.background without re-checking the HTTP method or matching the stored route detail.

This matters because RemoveProjectBackground() is a real destructive operation:

• It checks project update rights.
• It deletes the background file if present.
• It clears the project's BackgroundFileID.

PoC

1. Log in as a user who can update a project that already has a background.
2. Create an API token with only: {"projects":["background"]}
3. Send: DELETE /api/v1/projects/<project_id>/background Authorization: Bearer <token>
4. Observe that the request succeeds and the project background is removed.

For comparison:

1. Create an API token with only: {"projects":["background_delete"]}
2. Repeat the same DELETE request.
3. Observe that the request is rejected with 401 Unauthorized.

I confirmed this locally with three validations:

1. /api/v1/routes advertises both background and background_delete.
2. The matcher unit test proves CanDoAPIRoute() accepts DELETE for background.
3. The webtest proves a real API token with only background successfully deletes the background.

Impact

Scoped API tokens can exceed their intended capability. A token intended for project background access can delete project backgrounds, which weakens the trust model for automation and third-party integrations that rely on narrowly scoped tokens.

The attacker needs a valid API token created by a user who has update rights on the target project, but the token itself only needs the weaker projects.background permission.

Vikunja: Scoped API tokens with projects.background permission can delete project backgrounds 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 v2.3.0.

This update for govulncheck-vulndb fixes the following issues:

• Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

• GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
• GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
• GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
• GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
• GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
• GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
• GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
• GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
• GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
• GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
• GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
• GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
• GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
• GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
• GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
• GO-2026-5933 GHSA-3g4q-2f67-2gvh
• GO-2026-5934 GHSA-59qp-cfj3-rp64
• GO-2026-5935 GHSA-7856-g3gv-9wq8
• GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
• GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
• GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
• GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
• GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
• GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
• GO-2026-5942 CVE-2026-46600
• GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
• GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
• GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
• GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
• GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
• GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
• GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
• GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
• GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
• GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
• GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
• GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
• GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
• GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
• GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
• GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
• GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
• GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
• GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
• GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
• GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
• GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
• GO-2026-5969 GHSA-g936-7jqj-mwv8
• GO-2026-5970 CVE-2026-56852
• GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
• GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
• GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
• GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
• GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
• GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
• GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
• GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
• GO-2026-5981 GHSA-mqxv-9rm6-w8qc
• GO-2026-5982 GHSA-pqg7-v6wh-3pfp
• GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
• GO-2026-5985 GHSA-7rx3-5wx3-5v76
• GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
• GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
• GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
• GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
• GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
• GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
• GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
• GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
• GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
• GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
• GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
• GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
• GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
• GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
• GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
• GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…