CVE-2020-35498Network attack vector

Network traffic disruption via excess Ethernet padding

Published Feb 11, 2021 · Updated Apr 23, 2025

Packet parsing in Open vSwitch allows remote attackers to interrupt network traffic by sending padded IPv4 or IPv6 packets. The userspace parser rejects Ethernet padding longer than 255 bytes after Layer 2, so the classifier builds a megaflow without expected Layer 3 and Layer 4 fields. Any packet source reaching an OVS datapath, including a tunneled host or guest VM, can seed an overly broad cached drop flow that continues discarding legitimate traffic.

CVSS severity7.5
High
EPSS probability8.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Packet parsing in Open vSwitch allows remote attackers to interrupt network traffic by sending padded IPv4 or IPv6 packets. The userspace parser rejects Ethernet padding longer than 255 bytes after Layer 2, so the classifier builds a megaflow without expected Layer 3 and Layer 4 fields. Any packet source reaching an OVS datapath, including a tunneled host or guest VM, can seed an overly broad cached drop flow that continues discarding legitimate traffic.

The record

CVE
CVE-2020-35498
Published
Feb 11, 2021
Updated
Apr 23, 2025
Vendor
Open vSwitch
Product
Open vSwitch
Classifications
CWE-400, T1498
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=openvswitch 2.5.12, openvswitch 2.6.10, openvswitch 2.7.13, openvswitch 2.8.11, openvswitch 2.9.9, openvswitch 2.10.7, openvswitch 2.11.6, openvswitch 2.12.3, openvswitch 2.13.3, openvswitch 2.14.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Open vSwitch · Open vSwitchversion=openvswitch 2.5.12, openvswitch 2.6.10, openvswitch 2.7.13, openvswitch 2.8.11, openvswitch 2.9.9, openvswitch 2.10.7, openvswitch 2.11.6, openvswitch 2.12.3, openvswitch 2.13.3, openvswitch 2.14.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1498Network Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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