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ftp: crafted FTP traffic can cause quadratic CPU consumption

High
jasonish published GHSA-w394-3g33-3jg9 Jul 21, 2026

Software

Suricata

Affected versions

>= 8.0.5, < 8.0.6

Patched versions

8.0.6

Description

Impact

Suricata's FTP parser could continue to allocate new transactions after the configured app-layer.protocols.ftp.max-tx threshold was reached while processing a large chunk of FTP command data. Crafted FTP traffic could therefore make Suricata spend excessive CPU in quadratic transaction handling, degrading packet processing and potentially causing loss of monitoring visibility or denial of service.

Patches

Upgrade to Suricata 8.0.6.

Workarounds

Disable FTP application-layer parsing for untrusted traffic until upgraded, for example by setting app-layer.protocols.ftp.enabled: no if FTP inspection is not required.

References

https://redmine.openinfosecfoundation.org/issues/8592

Credits

OSS-Fuzz.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVE ID

CVE-2026-63447

Weaknesses

Inefficient Algorithmic Complexity

An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached. Learn more on MITRE.