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FreeBSDOperating system

CVE-2009-0641

HIGH · 9.3 CVSS v2.0 Published 2009-02-20
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
sys_term.c in telnetd in FreeBSD 7.0-RELEASE and other 7.x versions deletes dangerous environment variables with a method that was valid only in older FreeBSD distributions, which might allow remote attackers to execute arbitrary code by passing a crafted environment variable from a telnet client, as demonstrated by an LD_PRELOAD value that references a malicious library.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FreeBSDOperating system
Affected:= 7.0= 7.0-release= 7.0_beta4= 7.0_releng= 7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:N/C:C/I:C/A:C

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch security.freebsd.org →
Recommended fix High confidence

FreeBSD 7.4-RELEASE (last 7.x stable) or migrate to FreeBSD 12.x/13.x for active support

  1. 1. Backup all critical data and configurations from the affected FreeBSD 7.0 system
  2. 2. Obtain the FreeBSD 7.4-RELEASE or later version ISO from the FreeBSD archives (https://download.freebsd.org//releases/)
  3. 3. Upgrade the system using freebsd-update or a fresh installation to FreeBSD 7.4-RELEASE (the last 7.x stable release)
  4. 4. After upgrade, verify telnetd is not running (telnet service is disabled by default in newer FreeBSD)
  5. 5. If telnetd is required, ensure it is updated to the patched version from the security advisory
  6. 6. Review /etc/inetd.conf to ensure telnet service is properly configured if needed
  7. 7. Consider migrating to a currently supported FreeBSD branch (12.x or 13.x) for long-term security support
Caveat FreeBSD 7.x reached end-of-life; applications may require recompilation; some configuration changes may be needed between major versions

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2009-0641 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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