Openvswitch: open vswitch: denial of service via malformed ftp epasv command
Summary
| CVE | CVE-2026-34956 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-05 16:16:11 UTC |
| Updated | 2026-05-05 19:31:10 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 5.9 MEDIUM from [email protected]
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Problem Types: CWE-120 | CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 5.9 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 5.9 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 7 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 8 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Fast Datapath For RHEL 9 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 13 Queens | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 13 Queens | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 13 Queens | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 16.2 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 16.2 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 17.1 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 17.1 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenStack Platform 18.0 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-34956 | [email protected] | access.redhat.com | |
| www.openwall.com/lists/oss-security/2026/03/31/15 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank Seiji Sakurai for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-03-31T00:00:00.000Z | Reported to Red Hat. |
| CNA | 2026-03-31T00:00:00.000Z | Made public. |
Workarounds
CNA: Optionally, avoid using alg=ftp flows. These are not usually configured.
There are currently no legacy QID mappings associated with this CVE.