CVE-2020-14405Network attack vector

Authenticated client crash via oversized TextChat allocation

Published Jun 17, 2020 · Updated Aug 4, 2024

Resource exhaustion in LibVNCServer before 0.9.13 allows remote authenticated users to crash VNC clients via oversized TextChat messages. HandleRFBServerMessage in libvncclient/rfbproto.c trusts the server-supplied TextChat length and allocates length plus one byte without an upper bound. A malicious VNC server must establish a session with an affected client; the bounded impact is client process termination and service interruption.

CVSS severity6.5
Medium
EPSS probability1.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in LibVNCServer before 0.9.13 allows remote authenticated users to crash VNC clients via oversized TextChat messages. HandleRFBServerMessage in libvncclient/rfbproto.c trusts the server-supplied TextChat length and allocates length plus one byte without an upper bound. A malicious VNC server must establish a session with an affected client; the bounded impact is client process termination and service interruption.

The record

CVE
CVE-2020-14405
Published
Jun 17, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, CAPEC-130, T1499
Attack vector
network
Privileges
authenticated

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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CAPEC-130Excessive Allocation
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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