Vulnerability · Published May 5, 2026 · Assigned by redhat
CVE-2026-34956Openvswitch: open vswitch: denial of service via malformed ftp epasv command
Medium 5.9
In plain English
A medium-severity buffer overflow in Fast Datapath for RHEL 7 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | openvswitch | no fix listed | DEBIAN-CVE-2026-34956 |
| Debian:13 | openvswitch | no fix listed | DEBIAN-CVE-2026-34956 |
| Debian:14 | openvswitch | 3.7.1-1 | DEBIAN-CVE-2026-34956 |
| Ubuntu:22.04:LTS | openvswitch | no fix listed | UBUNTU-CVE-2026-34956 |
| Ubuntu:24.04:LTS | openvswitch | no fix listed | UBUNTU-CVE-2026-34956 |
| Ubuntu:25.10 | openvswitch | no fix listed | UBUNTU-CVE-2026-34956 |
| Ubuntu:26.04:LTS | openvswitch | no fix listed | UBUNTU-CVE-2026-34956 |
Affected products (as reported)
Weakness: CWE-120 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://access.redhat.com/security/cve/CVE-2026-34956 vdb-entry, x_refsource_REDHAT
- RHBZ#2453459 issue-tracking, x_refsource_REDHAT
- http://www.openwall.com/lists/oss-security/2026/03/31/15