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SuricataApplication · Suricata Ids

CVE-2019-16410

CRITICAL · 9.1 CVSS v3.1 Published 2019-09-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in Suricata 4.1.4. By sending multiple fragmented IPv4 packets, the function Defrag4Reassemble in defrag.c tries to access a memory region that is not allocated, because of a lack of header_len checking.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Suricata 4.1.4 contains a memory access vulnerability in the Defrag4Reassemble function in defrag.c. When processing fragmented IPv4 packets, the function attempts to access a memory region that has not been allocated due to insufficient header_len validation. This allows a remote attacker to trigger an out-of-bounds memory read by sending specially crafted fragmented IPv4 packets.

MitigationUpgrade Suricata to the latest patched version. As a compensating control, implement network-level filtering to drop malformed or suspicious IPv4 fragment sequences before they reach Suricata.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SuricataApplication
Affected:= 4.1.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Suricata version
    Run 'suricata --version' or check package manager (dpkg -l suricata, rpm -qi suricata)
    Affected if Version reported is 4.1.4 exactly
  2. Locate Suricata configuration file
    Common paths: /etc/suricata/suricata.yaml, /etc/suricata.yaml, or check documentation for your installation
    Affected if Configuration file exists and defrag settings can be inspected
  3. Verify defragmentation is enabled
    In the configuration file, search for 'defrag' or 'fragmentation' settings under the host or network configuration sections. Look for 'defrag: yes' or similar enablement flags
    Affected if IPv4 defragmentation is explicitly enabled in the configuration
  4. Confirm active traffic processing mode
    Check if Suricata is running in inline or passive mode (ps aux | grep suricata, systemctl status suricata). Review configuration for 'interface' or 'pcap' settings showing active packet capture
    Affected if Suricata is actively capturing and processing network traffic on interfaces
  5. Review defrag configuration parameters
    In suricata.yaml, locate 'defrag' section and check for 'max-header-len' or 'header-len' validation settings if exposed
    Affected if Defrag configuration exists but header_len validation is set to default or not explicitly hardened

You are affected if Suricata version 4.1.4 is installed AND defragmentation for IPv4 packets is enabled AND Suricata is actively processing network traffic where malformed fragments could be received.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Suricata to the latest patched version. As a compensating control, implement network-level filtering to drop malformed or suspicious IPv4 fragment sequences before they reach Suricata.

Recommended fix Moderate confidence

Suricata 5.0.0 or later (5.x branch)

  1. 1. Back up current Suricata configuration files (/etc/suricata/ directory)
  2. 2. Stop the Suricata service: 'systemctl stop suricata' or 'service suricata stop'
  3. 3. Upgrade Suricata to version 5.0.0 or later using your package manager or source compilation
  4. 4. Verify the installation: 'suricata --version'
  5. 5. Validate the configuration: 'suricata -T -c /etc/suricata/suricata.yaml'
  6. 6. Start the Suricata service: 'systemctl start suricata' or 'service suricata start'
  7. 7. Monitor logs for any errors after restart
Caveat Major version upgrade from 4.x to 5.x may introduce configuration changes; review the Suricata 5.0 release notes for any breaking changes to rulesets or configuration syntax

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Suricata Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing10.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,100
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-16410 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data