# CVE-2017-5202: tcpdump buffer overflow in ISO CLNS parser

Source: https://junglewise.ai/threats/cve-2017-5202-tcpdump-buffer-overflow-in-iso-clns-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2017-01-28. Updated: 2026-05-13  
License: CC BY 4.0 with a link back

CVE-2017-5202 · Severity: critical · CVSS 9.8 · Published 2017-01-28

tcpdump is a widely used command-line tool for monitoring and analyzing network traffic. A vulnerability in its ISO CLNS protocol parser allows an attacker to trigger a buffer overflow by sending specially crafted network packets. This could lead to a complete system crash or allow the attacker to gain unauthorized control over the system running the tool.

## Quick answers

**Is CVE-2017-5202 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2017-5202 being exploited in the wild.

**How severe is CVE-2017-5202?** Critical severity, with a CVSS score of 9.8, published 28 January 2017.

**Which products and versions are affected?** tcpdump tcpdump < 4.9.0.

**Is there a fix for CVE-2017-5202?** A patch was published on 2017-01-29: Debian released security update DSA-3775-1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2017-5202 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2017-5202?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A buffer overflow vulnerability exists in tcpdump versions prior to 4.9.0 within the ISO CLNS (Connectionless Network Service) parser. The flaw is located in the clnp_print() function in print-isoclns.c and is triggered during the processing of malformed packets. A remote, unauthenticated attacker can exploit this by sending specially crafted network traffic to a segment where tcpdump is performing live capture, or by tricking a user into opening a malicious pcap file. Successful exploitation can result in a denial of service (application crash) or potentially arbitrary code execution with the privileges of the tcpdump process. The issue was addressed in version 4.9.0.

## Affected products

- tcpdump tcpdump < 4.9.0

## Timeline

- 2017-01-26: disclosed: Vulnerability reported in Debian bug tracking system
- 2017-01-27: advisory: NVD publication date
- 2017-01-29: patched: Debian released security update DSA-3775-1

## References

- [http://www.debian.org/security/2017/dsa-3775](http://www.debian.org/security/2017/dsa-3775)
- [http://www.securityfocus.com/bid/95852](http://www.securityfocus.com/bid/95852)
- [http://www.securitytracker.com/id/1037755](http://www.securitytracker.com/id/1037755)
- [https://access.redhat.com/errata/RHSA-2017:1871](https://access.redhat.com/errata/RHSA-2017:1871)
- [https://security.gentoo.org/glsa/201702-30](https://security.gentoo.org/glsa/201702-30)
- [https://www.mail-archive.com/debian-bugs-dist%40lists.debian.org/msg1494526.html](https://www.mail-archive.com/debian-bugs-dist%40lists.debian.org/msg1494526.html)