CVE-2020-14398Network attack vector

Client hang via unbounded socket-read retries

Published Jun 17, 2020 · Updated Aug 4, 2024

Infinite loop in LibVNCClient before 0.9.13 allows remote attackers to hang VNC clients through half-open TCP connections. ReadFromRFBServer repeatedly treats EAGAIN or EWOULDBLOCK read failures as retryable while select returns no data, without enforcing a retry limit. The client must connect to a remote VNC endpoint that becomes half-open; the affected process remains trapped in the read loop and loses availability.

CVSS severity7.5
High
EPSS probability2.76%
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 LibVNCClient before 0.9.13 allows remote attackers to hang VNC clients through half-open TCP connections. ReadFromRFBServer repeatedly treats EAGAIN or EWOULDBLOCK read failures as retryable while select returns no data, without enforcing a retry limit. The client must connect to a remote VNC endpoint that becomes half-open; the affected process remains trapped in the read loop and loses availability.

The record

CVE
CVE-2020-14398
Published
Jun 17, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 17, 2020CVE 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

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NVDCVSS: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-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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