Description
isakmp_sub_print in tcpdump 3.6 through 3.7.1 allows remote attackers to cause a denial of service (CPU consumption) via a certain malformed ISAKMP packet to UDP port 500, which causes tcpdump to enter an infinite loop.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | tcpdump | 3.7.1-1.2 | — |
| Debian 13 | tcpdump | 3.7.1-1.2 | — |
| Debian 12 | tcpdump | 3.7.1-1.2 | — |
| Debian 3.0 | tcpdump | 3.6.2-2.3 | DSA-255 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- TCPDump 3.x - Malformed ISAKMP Packet Denial of Service EDB-22294 · dos · Mar 1, 2003 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- DSA-255 tcpdump - infinite loop Debian Security (DSA / DLA) · Mar 9, 2026
References
- http://www.idefense.com/advisory/02.27.03.txt
- 20030304 [OpenPKG-SA-2003.014] OpenPKG Security Advisory (tcpdump) mailing-list
- MDKSA-2003:027 vendor-advisory
- 6974 vdb-entry
- RHSA-2003:214 vendor-advisory
- DSA-255 vendor-advisory
- 20030227 iDEFENSE Security Advisory 02.27.03: TCPDUMP Denial of Service Vulnerability in ISAKMP Packet Parsin mailing-list
- RHSA-2003:085 vendor-advisory
- RHSA-2003:032 vendor-advisory
- tcpdump-isakmp-dos(11434) vdb-entry
- CLA-2003:629 vendor-advisory
- SuSE-SA:2003:0015 vendor-advisory