Vulnerability Note VU#776781

tcpdump vulnerable to buffer overflow via parsing of AFS ACL packets

Original Release date: 22 Jun 2001 | Last revised: 26 Jun 2001


Tcpdump version 3.5 contains a buffer overflow vulnerability permitting unauthorized remote root access.


Tcpdump version 3.5 added support for handling AFS packets. Unfortunately the code responsible for printing AFS access control lists contains an unchecked buffer that can be overflowed by a remote attacker by sending a crafted AFS packet into the target network. Any machine on the target network that is running tcpdump with a large (> ~500) snaplen argument when the hostile packet arrives can be made to execute arbitrary code. Since tcpdump requires root privileges in order to run, the arbitrary code will also run with root privileges. Fixed in version 3.6.1.

Note that a program that successfully exploits this vulnerability was publicly released on the BugTraq mailing list on January 11, 2001.


Attackers can remotely execute arbitrary code with root privileges on a vulnerable host.


Upgrade to version 3.6.1 or greater.

Filter incoming dst UDP 7000 packets from untrusted networks. Exclude dst UDP 7000 packets from tcpdump capture, e.g. "tcpdump not udp dst port 7000".

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
FreeBSD.orgAffected-21 Jun 2001
MandrakeSoftAffected-21 Jun 2001
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



First public disclosure by and the !Hispahack Research Team.

Other Information

  • CVE IDs: CVE-2000-1026
  • Date Public: 11 Jan 2001
  • Date First Published: 22 Jun 2001
  • Date Last Updated: 26 Jun 2001
  • Severity Metric: 16.03
  • Document Revision: 16


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