# CVE-2026-63198: traQ: Privilege escalation by OAuth prompt=none request

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

traQ is a messenger application built for Digital Creators Club traP. Prior to 3.28.3, OAuth2 silent authorization requests using prompt=none with an empty or omitted scope parameter check prior consent against the empty requested scope set even though all scopes registered for the client become eligible for issuance. An attacker who controls an OAuth client capable of receiving authorization codes can target a user who previously consented to only some client scopes and obtain an access token containing broader registered scopes without additional consent. A user who has never consented to the client still receives consent_required. This issue is fixed in version 3.28.3.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- traPtitech / traQ: < 3.28.3 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 7.3 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-863

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/traPtitech/traQ/security/advisories/GHSA-8cfq-jgf7-8m27 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/traPtitech/traQ/commit/5510fe8aa9bb15fc4755c78792381dbb03d576c3 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/traPtitech/traQ/releases/tag/v3.28.3 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-63198; retrieved 2026-11-03; source updated 2026-11-03

Revision: 30d2fe73eb6c70c4848694ef62aeb1ee98e4bfd40d95359cf64b29a4d92aa301

Canonical: https://y2.dev/cve/CVE-2026-63198

## 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.