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.

Published: 2026-05-05 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Awaiting Analysis，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-34956 is rated Low Risk (35.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.40%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-34956

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.10% 0.40% +0.31%
2 2026-05-06 — 0.10% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34956

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]

Weakness enumeration for CVE-2026-34956

GitHub Security Advisory for CVE-2026-34956

GHSA-q5f5-xxh8-jx9h · Severity: medium — A flaw was found in Open vSwitch. When Open vSwitch is configured with a conntrack flow using FTP...

OS Trackers for CVE-2026-34956

vendor priority summary link
debian not yet assigned CVE-2026-34956 not yet assigned priority: Debian including 1 source packages (openvswitch), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-34956
suse medium CVE-2026-34956 severity moderate: SUSE including 62 source package names (libopenvswitch-2_11-0-2.11.5-3.30.1, libopenvswitch-2_14-0-2.14.2-150400.24.32.1, …), 63 product×package rows across 7 product lines (SUSE Linux Enterprise Micro 5.5, SUSE Linux Enterprise Module for Package Hub 15 SP7, … (7 product lines)): Fixed 45, First Fixed 17, Known Not Affected 1. https://www.suse.com/security/cve/CVE-2026-34956/
ubuntu medium CVE-2026-34956 medium priority: Ubuntu including 1 source packages (openvswitch), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): needs-triage 6, not-affected 1, released 1. https://ubuntu.com/security/CVE-2026-34956

Affected software / configurations for CVE-2026-34956

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-34956

cvelogic Threat Intelligence