CVE-2003-1029: The L2TP protocol parser in tcpdump 3.8.1 and earlier allows remote attackers to cause a denial of service (in

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MEDIUM 5.0DOWNGRADE

CVE-2003-1029 is a medium-severity flaw (CVSS 5.0) affecting tcpdump. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

EPSS top 4%: very likely to be exploited
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	9.9% (top 4%)
CISA exploited list	No
Published	2004-02-17
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: lbl

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2004-02-17 05:00 UTCPublished CVE record published
2026-06-16 22:03 UTCUpdated Record last modified

lbl tcpdump DOWNGRADE

Affected: 3.4 · 3.5 · 3.5.2 · 3.6.2 · 3.6.3 · 3.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.4

1. Check installed version

apt-cache policy tcpdump || rpm -q tcpdump || tcpdump --version

2. No fixed release: DOWNGRADE to a release before 3.4 (Debian / Ubuntu)

apt-cache madison tcpdump sudo apt install tcpdump=<VERSION_BEFORE_3.4> sudo apt-mark hold tcpdump

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list tcpdump sudo dnf downgrade tcpdump-<VERSION_BEFORE_3.4> sudo dnf versionlock add tcpdump

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Tcpdump 3.x - L2TP Parser Remote Denial of Service

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2003-1029?

tcpdump: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2003-1029 being exploited?

CVE-2003-1029 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2003-1029 affect?

CVE-2003-1029 affects tcpdump. Severity is medium (CVSS 5.0). 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 leng

How urgent is CVE-2003-1029?

Priority 46/100. EPSS top 4%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2018-16301 HIGH 7.8 UPGRADE The command-line argument parser in tcpdump before 4.99.0 has a buffer overflow in tcpdump.c:read_infile()
CVE-1999-1024 HIGH 7.5 DOWNGRADE ip_print procedure in Tcpdump 3.4a allows remote attackers to cause a denial of service via a packet with a ze
CVE-2000-1026 HIGH 10.0 DOWNGRADE Multiple buffer overflows in LBNL tcpdump allow remote attackers to execute arbitrary commands.
CVE-2023-1801 MEDIUM 6.5 DOWNGRADE The SMB protocol decoder in tcpdump version 4.99.3 can perform an out-of-bounds write when decoding a crafted
CVE-2020-8037 HIGH 7.5 DOWNGRADE MITIGATE The ppp decapsulator in tcpdump 4.9.3 can be convinced to allocate a large amount of memory.

References

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