# CVE-2016-7939: tcpdump buffer overflow in GRE parser

Source: https://junglewise.ai/threats/cve-2016-7939-tcpdump-buffer-overflow-in-gre-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-2016-7939 · 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 GRE protocol parser allows an attacker to send specially crafted network packets that can cause the application to crash or potentially execute unauthorized code. This could lead to a denial of service or a compromise of the system running the network analysis tool.

Technologies: [Tcpdump](https://junglewise.ai/threats/technologies/tcpdump). Vendors: [Tcpdump](https://junglewise.ai/threats/vendors/tcpdump).

## Quick answers

**Is CVE-2016-7939 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2016-7939 being exploited in the wild.

**How severe is CVE-2016-7939?** 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-2016-7939?** A patch was published on 2017-01-28: Fixed in version 4.9.0-1 in Debian and upstream 4.9.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2016-7939 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2016-7939?** Check whether you run Tcpdump. 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 the GRE (Generic Routing Encapsulation) parser of tcpdump versions prior to 4.9.0. The flaw is located within multiple functions in the print-gre.c source file. A remote, unauthenticated attacker can exploit this by sending specially crafted GRE packets to a network segment where tcpdump is performing live capture, or by tricking a user into opening a malicious pcap file. Successful exploitation can result in a crash (Denial of Service) 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

- 2017-01-27: disclosed
- 2017-01-27: advisory
- 2017-01-28: patched: Fixed in version 4.9.0-1 in Debian and upstream 4.9.0

## 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)

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