Description
The L2TP protocol parser in tcpdump 3.8.1 and earlier allows remote attackers to cause a denial of service (infinite loop and memory consumption) via a packet with invalid data to UDP port 1701, which causes l2tp_avp_print to use a bad length value when calling print_octets.
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 | 3.8.3-1 | — |
| Debian 13 | tcpdump | 3.8.3-1 | — |
| Debian 12 | tcpdump | 3.8.3-1 | — |
| Debian 3.0 | tcpdump | 3.6.2-2.7 | DSA-425 |
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 - L2TP Parser Remote Denial of Service EDB-23452 · dos · Dec 20, 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-425 tcpdump - multiple vulnerabilities Debian Security (DSA / DLA) · Mar 9, 2026
References
- 10718 third-party-advisory
- 10668 third-party-advisory
- [tcpdump-workers] 20031224 Seg fault of tcpdump (v 3.8.1 and below) with malformed l2tp packets mailing-list
- 10636 third-party-advisory
- 1008748 vdb-entry
- ESA-20040119-002 vendor-advisory
- MDKSA-2004:008 vendor-advisory
- 20040119 [ESA-20040119-002] 'tcpdump' multiple vulnerabilities. mailing-list
- DSA-425 vendor-advisory
- 10652 third-party-advisory
- 20031221 Re: Remote crash in tcpdump from OpenBSD mailing-list
- 20031220 Remote crash in tcpdump from OpenBSD mailing-list