# CVE-2026-123527: Vikunja 2.4.0 before 2.7.1 API Token Scope Collision Authorization Bypass

Status: published. Published: 2026-11-08. Updated: 2026-11-12.

Vikunja from 2.4.0 before 2.7.1 contains an authorization bypass vulnerability that allows token holders to perform unintended operations due to colliding v1 and v2 API token permission keys. Attackers with a token scoped to read project backgrounds can delete them via the v2 DELETE background route, and bucket create-only tokens can update existing buckets.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- go-vikunja / vikunja (code.vikunja.io/api): ≥ 2.4.0; < 2.7.1 (affected, semver); 2.7.1 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L; source: CNA: VulnCheck

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.24% as of 2026-11-12; percentile 14.93%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-863

## Exploit evidence

- exploit: https://github.com/go-vikunja/vikunja/security/advisories/GHSA-j5v7-qcwp-5g32 (ADP: CISA-ADP)

## References

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-j5v7-qcwp-5g32 (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/vikunja-2.4.0-before-2.7.1-api-token-scope-collision-authorization-bypass (CNA: VulnCheck; third-party-advisory)

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-j5v7-qcwp-5g32 (ADP: CISA-ADP; exploit)

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-j5v7-qcwp-5g32 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/vikunja-2.4.0-before-2.7.1-api-token-scope-collision-authorization-bypass (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123527; retrieved 2026-11-12; source updated 2026-11-12

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123527; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-123527; retrieved 2026-11-12; source updated Not reported

Revision: 4c6dafa7c76013be15f93c966b709a1c194fd448e7979d5bb6b8337f31f2483c

Canonical: https://y2.dev/cve/CVE-2026-123527

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.