# CVE-2016-7993: Tcpdump buffer overflow in relts_print function

Source: https://junglewise.ai/threats/cve-2016-7993-tcpdump-buffer-overflow-in-relts-print-function  
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-2016-7993 · Severity: critical · CVSS 9.8 · Published 2017-01-28

A vulnerability was found in tcpdump, a widely used tool for monitoring and analyzing network traffic. By sending specially crafted network packets, an attacker could cause the tool to crash or potentially execute unauthorized code. This could disrupt network monitoring operations or allow an attacker to gain a foothold on the system running the analysis software.

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

## Quick answers

**Is CVE-2016-7993 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2016-7993 being exploited in the wild.

**How severe is CVE-2016-7993?** Critical severity, with a CVSS score of 9.8, published 28 January 2017.

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

**Is there a fix for CVE-2016-7993?** A patch was published on 2017-01-26: Upstream release 4.9.0 published Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2016-7993 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2016-7993?** 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 relts_print() function within util-print.c of tcpdump versions prior to 4.9.0. The flaw is triggered during the parsing of relative timestamps in several protocol handlers, including DNS, DVMRP, HSRP, IGMP, lightweight resolver protocol, and PIM. An attacker can exploit this by sending specially crafted packets over the network or providing a malicious pcap file for offline analysis. Successful exploitation can lead to a crash (Denial of Service) or potentially arbitrary code execution with the privileges of the tcpdump process. The issue is addressed in tcpdump version 4.9.0.

## Affected products

- tcpdump tcpdump before 4.9.0

## Timeline

- 2016-10-13: disclosed: CVE assigned date
- 2017-01-26: patched: Upstream release 4.9.0 published
- 2017-01-28: advisory: NVD publication date

## 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)

## Related threats

- [Tcpdump buffer overflow in ISO CLNS parser](https://junglewise.ai/threats/cve-2017-5486-tcpdump-buffer-overflow-in-iso-clns-parser)
- [Tcpdump buffer overflow in ISO CLNS parser lookup_nsap function](https://junglewise.ai/threats/cve-2017-5485-tcpdump-buffer-overflow-in-iso-clns-parser-lookup-nsap-function)
- [Tcpdump buffer overflow in ATM parser sig_print function](https://junglewise.ai/threats/cve-2017-5484-tcpdump-buffer-overflow-in-atm-parser-sig-print-function)
- [tcpdump buffer overflow in SNMP parser](https://junglewise.ai/threats/cve-2017-5483-tcpdump-buffer-overflow-in-snmp-parser)
- [tcpdump buffer overflow in Q.933 parser](https://junglewise.ai/threats/cve-2017-5482-tcpdump-buffer-overflow-in-q-933-parser)