What’s Vulnerable › Vulnerabilities

CVE-2026-34956: Openvswitch: open vswitch: denial of service via malformed ftp epasv command

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-05 · updated 2026-10-26
• Weakness: CWE-120

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.

Affected products

• Red Hat Fast Datapath for RHEL 7: all versions
• Red Hat Fast Datapath for RHEL 8: all versions
• Red Hat Fast Datapath for RHEL 9: all versions
• Red Hat OpenShift Container Platform 4.18: all versions
• Red Hat Enterprise Linux 7: all versions
• Red Hat OpenStack Platform 13 (Queens): all versions
• Red Hat OpenStack Platform 16.2: all versions
• Red Hat OpenStack Platform 17.1: all versions
• Red Hat OpenStack Platform 18.0: all versions

References

• https://access.redhat.com/security/cve/CVE-2026-34956
• https://bugzilla.redhat.com/show_bug.cgi?id=2453459
• http://www.openwall.com/lists/oss-security/2026/03/31/15

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