CVE-2018-6794: Suricata before 4.0.4 is prone to an HTTP detection bypass vulnerability in detect.c and stream-tcp.c

Q: How do I fix CVE-2018-6794?

suricata: upgrade to 4.0.4; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2018-6794 being exploited?

CVE-2018-6794 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2018-6794 affect?

CVE-2018-6794 affects suricata, debian linux. Severity is medium (CVSS 5.3). Suricata before 4.0.4 is prone to an HTTP detection bypass vulnerability in detect.c and stream-tcp.c. If a malicious server breaks a normal TCP flow and sends data before the 3-way handshake is complete, then the data sent by the malicious

Q: How urgent is CVE-2018-6794?

Priority 58/100. EPSS top 2%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

MEDIUM 5.3REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2018-6794 is a medium-severity flaw (CVSS 5.3) affecting suricata, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Suricata before 4.0.4 is prone to an HTTP detection bypass vulnerability in detect.c and stream-tcp.c. If a malicious server breaks a normal TCP flow and sends data before the 3-way handshake is complete, then the data sent by the malicious server will be accepted by web clients such as a web browser or Linux CLI utilities, but ignored by Suricata IDS signatures. This mostly affects IDS signatures for the HTTP protocol and TCP stream content; sig

Why this priority

EPSS top 2%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	23.7% (top 2%)
CISA exploited list	No
Weakness	CWE-693
Published	2018-02-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · suricata-ids

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-02-07 05:29 UTCPublished CVE record published
2026-06-17 02:02 UTCUpdated Record last modified

suricata-ids suricata UPGRADE

Affected: < 4.0.4

Fixed in: 4.0.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 4.0.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade suricata

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade suricata

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

debian debian linux MITIGATE

Affected: 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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: Suricata < 4.0.4 - IDS Detection Bypass

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-2018-6794?

suricata: upgrade to 4.0.4; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-6794 being exploited?

CVE-2018-6794 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-2018-6794 affect?

CVE-2018-6794 affects suricata, debian linux. Severity is medium (CVSS 5.3). Suricata before 4.0.4 is prone to an HTTP detection bypass vulnerability in detect.c and stream-tcp.c. If a malicious server breaks a normal TCP flow and sends data before the 3-way handshake is complete, then the data sent by the malicious

How urgent is CVE-2018-6794?

Priority 58/100. EPSS top 2%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · Suricata and Snort vulnerabilities

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References

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