CVE-2007-1398: The frag3 preprocessor in Snort 2.6.1.1, 2.6.1.2, and 2.7.0 beta, when configured for inline use on Linux with

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HIGH 7.1WATCHLISTDOWNGRADE

CVE-2007-1398 is a high-severity flaw (CVSS 7.1) affecting snort. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The frag3 preprocessor in Snort 2.6.1.1, 2.6.1.2, and 2.7.0 beta, when configured for inline use on Linux without the ip_conntrack module loaded, allows remote attackers to cause a denial of service (segmentation fault and application crash) via certain UDP packets produced by send_morefrag_packet and send_overlap_packet.

Why this priority

High severity
EPSS top 7%: very likely to be exploited
Public exploit reference
On your watchlist

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

Risk facts

CVSS score	7.1 (High)
EPSS exploit chance	5.9% (top 7%)
CISA exploited list	No
Published	2007-03-10
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: snort

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

Am I affected?

Timeline

2007-03-10 22:19 UTCPublished CVE record published
2026-06-16 22:37 UTCUpdated Record last modified

snort snort DOWNGRADE

Affected: 2.6.1.1 · 2.6.1.2 · 2.7_beta1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.6.1.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.6.1.1 (Debian / Ubuntu)

apt-cache madison snort sudo apt install snort=<VERSION_BEFORE_2.6.1.1> sudo apt-mark hold snort

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

dnf --showduplicates list snort sudo dnf downgrade snort-<VERSION_BEFORE_2.6.1.1> sudo dnf versionlock add snort

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: Snort 2.6.1.1/2.6.1.2/2.7.0 - 'fragementation' 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-2007-1398?

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

Is CVE-2007-1398 being exploited?

CVE-2007-1398 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-2007-1398 affect?

CVE-2007-1398 affects snort. Severity is high (CVSS 7.1). The frag3 preprocessor in Snort 2.6.1.1, 2.6.1.2, and 2.7.0 beta, when configured for inline use on Linux without the ip_conntrack module loaded, allows remote attackers to cause a denial of service (segmentation fault and application crash

How urgent is CVE-2007-1398?

Priority 58/100. High severity; EPSS top 7%: very likely to be exploited; Public exploit reference; On your watchlist

Software pages

Suricata and Snort vulnerabilities

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References

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