Is CVE-2026-34956 in the CISA KEV catalog?

No. CVE-2026-34956 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-34956?

CVE-2026-34956 has a CVSS v3 base score of 5.9 (Moderate).

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

CVE-2026-34956 has an EPSS score of 0.40% (32th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-34956?

Upgrade openvswitch on debian unstable to 3.7.1-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-34956

MEDIUM

5.9

CVSS v3

NVD

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.

CWE-120Classic Buffer Overflow

How to fix

Remediation Available

openvswitchDebian

Fixed in:3.7.1-1CVE-2026-34956

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U

Exploit Intelligence

0.40%probability of exploitation in 30 days

32ndpercentile

Low risk: more likely to be exploited than 32% of all known CVEs.

References

Other references3

Related Vulnerabilities

Other CWE-120 (Classic Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0195	Medium	6.8	100%	-	Fix
CVE-2017-7269	Critical	9.8	100%	KEV	-
CVE-2019-11043	High	8.7	99%	KEV + Ransom	Fix
CVE-2011-4862	High	10.0	95%	-	Fix
CVE-2007-5659	High	7.8	94%	KEV	Fix
CVE-2022-3786	High	7.5	91%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-05.