CVE-2021-20024

Memory disclosure or crash via LLDP parsing

Published Jul 9, 2021 · Updated Aug 3, 2024

Out-of-bounds reads in SonicWall Switch 1.0.0.5-16 and earlier allow remote attackers on the same LAN to read memory or crash the switch. The LLDP handling path performs multiple reads beyond buffer boundaries while processing received protocol data; SonicWall has not disclosed the affected routines or fields. Exploitation requires Layer 2 access to the same LAN and can expose memory contents or destabilize the appliance, with no reported integrity impact.

CVSS severity8.1
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds reads in SonicWall Switch 1.0.0.5-16 and earlier allow remote attackers on the same LAN to read memory or crash the switch. The LLDP handling path performs multiple reads beyond buffer boundaries while processing received protocol data; SonicWall has not disclosed the affected routines or fields. Exploitation requires Layer 2 access to the same LAN and can expose memory contents or destabilize the appliance, with no reported integrity impact.

The record

CVE
CVE-2021-20024
Published
Jul 9, 2021
Updated
Aug 3, 2024
Vendor
SonicWall
Product
SonicWall Switch
Classifications
CWE-125, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=1.0.0.5-16 and earlier

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

SonicWall · SonicWall Switchversion=1.0.0.5-16 and earlier

Published CVSS scores

8.1NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
6.8NIST NVDAV:A/AC:L/Au:N/C:P/I:N/A:C

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint 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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