CVE-2026-34956

Openvswitch: open vswitch: denial of service via malformed ftp epasv command

Published May 5, 2026 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Workaround

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

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:enterprise_linux:7 cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Redhat fast Datapath
Redhat openshift Container Platform
Redhat openstack Platform
Redhat openvswitch
Vendors & Products Redhat fast Datapath
Redhat openshift Container Platform
Redhat openstack Platform
Redhat openvswitch
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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 5, 2026, 8:31 PM
Reserved
Mar 31, 2026, 5:43 PM
Status
Awaiting Analysis
Published
May 5, 2026, 4:16 PM
Modified
Nov 5, 2026, 9:18 PM