CVE-2021-20046Network attack vector

Denial of service via HTTP Content-Length overflow

Published Jan 7, 2022 · Updated Aug 3, 2024

Stack-based buffer overflow in SonicWall SonicOS 7.0.1-R146 and earlier allows remote authenticated attackers to cause denial of service. The HTTP response path mishandles an attacker-controlled Content-Length header in a stack buffer, permitting memory overwrite and potentially code execution. Access requires the SonicOS web management interface; exploitation can interrupt the firewall and may provide code execution, while no public proof of concept is reported.

CVSS severity8.8
High
EPSS probability1.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in SonicWall SonicOS 7.0.1-R146 and earlier allows remote authenticated attackers to cause denial of service. The HTTP response path mishandles an attacker-controlled Content-Length header in a stack buffer, permitting memory overwrite and potentially code execution. Access requires the SonicOS web management interface; exploitation can interrupt the firewall and may provide code execution, while no public proof of concept is reported.

The record

CVE
CVE-2021-20046
Published
Jan 7, 2022
Updated
Aug 3, 2024
Vendor
SonicWall
Product
SonicOS
Classifications
CWE-121, CWE-787, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 7, 2022CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=5.9.1.13 and earlier
  2. Affected versionversion=6.0.5.3-94o and earlier
  3. Affected versionversion=6.5.1.13-1n and earlier
  4. Affected versionversion=6.5.4.8-89n and earlier
  5. Affected versionversion=6.5.4.v_21s-1288 and earlier
  6. Affected versionversion=7.0.1-5018-R1715 and earlier
  7. Affected versionversion=7.0.1-5023-1349 and earlier
  8. Affected versionversion=7.0.1-R146 and earlier

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SonicWall · SonicOSversion=5.9.1.13 and earlier; version=6.0.5.3-94o and earlier; version=6.5.1.13-1n and earlier; version=6.5.4.8-89n and earlier; version=6.5.4.v_21s-1288 and earlier; version=7.0.1-5018-R1715 and earlier; version=7.0.1-5023-1349 and earlier; version=7.0.1-R146 and earlier

Published CVSS scores

6.5NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

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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