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No exploitation reportedFix availableAwaiting NVD analysis

CVE-2026-34956

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

No exploitation reported by the sources we read.

  • Published2026-05-05
  • WeaknessCWE-120

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-05-0515:45CVE publishedCNA

Versions per branch

Products declared by the CNA41 products

As redhat, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

35 more products in the CVE record.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-05

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • openvswitchUbuntu:Pro:18.04:LTSall versions · no fixed version listed
  • openvswitchUbuntu:26.04:LTSall versions · no fixed version listed
  • openvswitchUbuntu:25.10all versions · no fixed version listed
  • openvswitchUbuntu:24.04:LTSall versions · no fixed version listed
  • openvswitchUbuntu:22.04:LTSall versions · no fixed version listed
  • openvswitchUbuntu:20.04:LTSall versions · no fixed version listed
  • openvswitchSUSE:Linux Micro 6.2all versions · fixed in 3.5.4-160000.4.1
  • openvswitchSUSE:Linux Micro 6.1all versions · fixed in 3.1.7-slfo.1.1_3.1

19 more package ranges on OSV.dev

Vendor advisories

  • CVE-2026-34956 Red Hat Product Security190 known affected

    openvswitch: Open vSwitch: Denial of Service via malformed FTP EPASV command

    openvswitch as a component of Fast Datapath for RHEL 7 · openvswitch-devel as a component of Fast Datapath for RHEL 7 · openvswitch-ovn-central as a component of Fast Datapath for RHEL 7 · +187 more

Full record on NVD

Fix

  1. Workaround from the vendor Red Hat Product Security CVE-2026-34956 · 190 productsOptionally, avoid using alg=ftp flows. These are not usually configured.
  2. No fix available, says the vendor Red Hat Product Security CVE-2026-34956 · 190 productsFix deferred

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-05-05
Last Modified
2026-11-05
NVD status
Awaiting Analysis
MSRC Title
Openvswitch: open vswitch: denial of service via malformed ftp epasv command
GitHub Advisory
GHSA-q5f5-xxh8-jx9h

Frequently asked questions

What is CVE-2026-34956?

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.

Is CVE-2026-34956 actively exploited?

Active exploitation of CVE-2026-34956 has not been confirmed. Its EPSS score was 0.4% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-34956?

CVE-2026-34956 has a CVSS v3 base score of 5.9 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

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