NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
💎
💎 RubyGems
Not in CISA KEV
MEDIUM severity

Sinatra Cross-site Scripting vulnerabilityGHSA-mq35-wqvf-r23c

MEDIUMFix: sinatra/sinatra@1278686

GHSA-mq35-wqvf-r23c is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in sinatra. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for sinatra — see the affected versions and patch details below.

Also known asCVE-2018-11627
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.1%probability of exploitation in next 30 days
Lower Risk-0.04%
Lower risk than most CVEs82th percentile — riskier than 82% of all scored CVEsHighest risk
0.00%0.92%1.84%2.76%0.4%2.1%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
💎sinatra

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

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

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemssinatra≥ 2.0.0&&< 2.0.22.0.2bundle update sinatra --conservative

Affected Products

2 products · 3 configurations
Application
cloudformsredhat
2 versions
4.64.7
Application
sinatrasinatrarb
< 2.0.2
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Sinatra before 2.0.2 has XSS via the 400 Bad Request page that occurs up…

github.comNVDFeb 2019

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sinatra, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update sinatra to 2.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mq35-wqvf-r23c is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
ProductFixed inAdvisory
CloudForms Management Engine 5.10ansible-runner-0:1.1.2-2.el7arRHSA-2019:0212
CloudForms Management Engine 5.9cfme-0:5.9.8.1-1.el7cfRHSA-2019:0315

Frequently Asked Questions

Sinatra before 2.0.2 has XSS via the 400 Bad Request page that occurs upon a params parser exception.
O3 Security · Impact-Aware SCA

Is GHSA-mq35-wqvf-r23c in your dependencies?

Find it across RubyGems, including transitive dependencies.

Scan my dependencies How O3 SCA works
Sinatra Cross-site Scripting vulnerability (Medium 6.1)