CVE-2021-44718Network attack vector

Client hang via incorrect-side TLS hello processing

Published Sep 2, 2022 · Updated Aug 4, 2024

Infinite loop in the client component of wolfSSL 5.0.0 and earlier allows man-in-the-middle attackers to hang applications via crafted TLS traffic. The client module accepts TLS hello messages normally sent only to servers and enters an infinite processing loop. Exploitation requires a man-in-the-middle position on a TLS 1.2 or earlier connection and interrupts only the affected client application.

CVSS severity5.9
Medium
EPSS probability0.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in the client component of wolfSSL 5.0.0 and earlier allows man-in-the-middle attackers to hang applications via crafted TLS traffic. The client module accepts TLS hello messages normally sent only to servers and enters an infinite processing loop. Exploitation requires a man-in-the-middle position on a TLS 1.2 or earlier connection and interrupts only the affected client application.

The record

CVE
CVE-2021-44718
Published
Sep 2, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 2, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/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.

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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-835Loop with Unreachable Exit Condition ('Infinite Loop')
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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