CVE-2026-31931: Suricata is a network IDS, IPS and NSM engine

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-31931 is a high-severity flaw (CVSS 7.5) affecting suricata. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Suricata is a network IDS, IPS and NSM engine. From version 8.0.0 to before version 8.0.4, use of the "tls.alpn" rule keyword can cause Suricata to crash with a NULL dereference. This issue has been patched in version 8.0.4.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 71%)
CISA exploited list	No
Weakness	CWE-476
Published	2026-04-02
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: oisf

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-02 14:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

oisf suricata UPGRADE

Affected: >= 8.0.0 and < 8.0.4

Fixed in: 8.0.4

Safe to downgrade to: a release before 8.0.0

1. Check installed version

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

2. UPGRADE to 8.0.4 (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.

3. If no update is available yet, DOWNGRADE to a release before 8.0.0 (Debian / Ubuntu)

apt-cache madison suricata sudo apt install suricata=<VERSION_BEFORE_8.0.0> sudo apt-mark hold suricata

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list suricata sudo dnf downgrade suricata-<VERSION_BEFORE_8.0.0> sudo dnf versionlock add suricata

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.

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-2026-31931?

suricata: upgrade to 8.0.4. Exact commands for each OS are on this page.

Is CVE-2026-31931 being exploited?

CVE-2026-31931 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-2026-31931 affect?

CVE-2026-31931 affects suricata. Severity is high (CVSS 7.5). Suricata is a network IDS, IPS and NSM engine. From version 8.0.0 to before version 8.0.4, use of the "tls.alpn" rule keyword can cause Suricata to crash with a NULL dereference. This issue has been patched in version 8.0.4.

How urgent is CVE-2026-31931?

Priority 38/100. High severity; Remotely exploitable, no login, no user action

Software pages

Suricata and Snort vulnerabilities

Related CVEs

CVE-2026-31933 HIGH 7.5 UPGRADE Suricata is a network IDS, IPS and NSM engine
CVE-2026-31937 HIGH 7.5 UPGRADE Suricata is a network IDS, IPS and NSM engine
CVE-2026-31932 HIGH 7.5 UPGRADE Suricata is a network IDS, IPS and NSM engine
CVE-2026-31934 HIGH 7.5 UPGRADE Suricata is a network IDS, IPS and NSM engine
CVE-2026-31935 HIGH 7.5 UPGRADE Suricata is a network IDS, IPS and NSM engine

References

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