CVE-2015-5239Network attack vector

Host process crash via oversized VNC clipboard message

Published Jan 23, 2020 · Updated Aug 6, 2024

Integer overflow in QEMU's VNC display driver before 2.1.0 allows remote authenticated users to crash the host process. The protocol_client_msg parser trusts the 32-bit ClientCutText length and adds eight without a bound, so wraparound keeps vnc_client_read in a loop that repeatedly allocates buffers. Reachability requires an enabled VNC display and endpoint access; exploitation hangs or terminates the affected QEMU instance and its guest.

CVSS severity6.5
Medium
EPSS probability3.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in QEMU's VNC display driver before 2.1.0 allows remote authenticated users to crash the host process. The protocol_client_msg parser trusts the 32-bit ClientCutText length and adds eight without a bound, so wraparound keeps vnc_client_read in a loop that repeatedly allocates buffers. Reachability requires an enabled VNC display and endpoint access; exploitation hangs or terminates the affected QEMU instance and its guest.

The record

CVE
CVE-2015-5239
Published
Jan 23, 2020
Updated
Aug 6, 2024
Vendor
QEMU Project
Product
QEMU
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 23, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 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=before 2.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

QEMU Project · QEMUversion=before 2.1.0

Published CVSS scores

4.0NVDAV:N/AC:L/Au:S/C:N/I:N/A:P
6.5NVDCVSS: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 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-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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