CVE-2026-34956: Openvswitch: open vswitch: denial of service via malformed ftp epasv command
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.
Other sources
Openvswitch: open vswitch: denial of service via malformed ftp epasv command
— Microsoft
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-34956?
The severity of CVE-2026-34956 is medium with a CVSS score of 5.9.
How do I fix CVE-2026-34956?
Fixing CVE-2026-34956 involves updating Open vSwitch to the latest patched version that addresses this vulnerability.
What type of vulnerability is CVE-2026-34956?
CVE-2026-34956 is a denial of service vulnerability caused by malformed FTP EPASV commands.
Which software versions are affected by CVE-2026-34956?
CVE-2026-34956 affects Open vSwitch and specifically versions 3.3.0-2 and 3.3.0-3 from Microsoft.
What can an attacker do with CVE-2026-34956?
An attacker can exploit CVE-2026-34956 to crash Open vSwitch by sending a specially crafted FTP stream with an oversized EPASV command.