CVE-2020-7039Network attack vector

Guest-to-host code execution via IRC DCC overflow

Published Jan 16, 2020 · Updated Aug 4, 2024

Heap-based buffer overflow in libslirp 4.1.0 and QEMU 4.2.0 allows remote attackers to crash or execute code via IRC DCC traffic. In tcp_emu in tcp_subr.c, EMU_IRC passes the full mbuf size to snprintf after the destination pointer has advanced, overstating the remaining space and permitting an out-of-bounds write. The target must use QEMU user-mode SLiRP networking and process a crafted IRC DCC command; the result is a QEMU-process crash or code execution with that process's privileges.

CVSS severity5.6
Medium
EPSS probability3.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in libslirp 4.1.0 and QEMU 4.2.0 allows remote attackers to crash or execute code via IRC DCC traffic. In tcp_emu in tcp_subr.c, EMU_IRC passes the full mbuf size to snprintf after the destination pointer has advanced, overstating the remaining space and permitting an out-of-bounds write. The target must use QEMU user-mode SLiRP networking and process a crafted IRC DCC command; the result is a QEMU-process crash or code execution with that process's privileges.

The record

CVE
CVE-2020-7039
Published
Jan 16, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 16, 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

5.6NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

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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