A flaw was found in Open vSwitch. When Open vSwitch is configured with a conntrack flow using FTP helpers over the userspace datapath, a remote attacker can send a specially crafted FTP stream with an EPASV command exceeding 255 characters. This heap access error can lead to a crash, resulting in a Denial of Service (DoS) for the affected system.

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Fixes

Solution

No solution given by the vendor.


Workaround

Optionally, avoid using alg=ftp flows. These are not usually configured.

History

Tue, 05 May 2026 17:30:00 +0000

Type Values Removed Values Added
References

Tue, 05 May 2026 16:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in Open vSwitch. When Open vSwitch is configured with a conntrack flow using FTP helpers over the userspace datapath, a remote attacker can send a specially crafted FTP stream with an EPASV command exceeding 255 characters. This heap access error can lead to a crash, resulting in a Denial of Service (DoS) for the affected system.
Title Openvswitch: open vswitch: denial of service via malformed ftp epasv command
First Time appeared Redhat
Redhat enterprise Linux
Redhat openshift
Redhat openstack
Weaknesses CWE-120
CPEs cpe:/a:redhat:openshift:4
cpe:/a:redhat:openstack:13
cpe:/a:redhat:openstack:16.2
cpe:/a:redhat:openstack:17.1
cpe:/a:redhat:openstack:18.0
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:7::fastdatapath
cpe:/o:redhat:enterprise_linux:8::fastdatapath
cpe:/o:redhat:enterprise_linux:9::fastdatapath
Vendors & Products Redhat
Redhat enterprise Linux
Redhat openshift
Redhat openstack
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-05-05T16:36:17.493Z

Reserved: 2026-03-31T17:43:41.756Z

Link: CVE-2026-34956

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-05-05T16:16:11.927

Modified: 2026-05-05T19:31:10.400

Link: CVE-2026-34956

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-05T18:00:13Z

Weaknesses