CVE-2020-10756: An out-of-bounds read vulnerability was found in the SLiRP networking implementation of the QEMU emulator

Routine

MEDIUM 6.5WATCHLISTUPGRADEDOWNGRADEMITIGATE

CVE-2020-10756 is a medium-severity flaw (CVSS 6.5) affecting libslirp, openstack, enterprise linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An out-of-bounds read vulnerability was found in the SLiRP networking implementation of the QEMU emulator. This flaw occurs in the icmp6_send_echoreply() routine while replying to an ICMP echo request, also known as ping. This flaw allows a malicious guest to leak the contents of the host memory, resulting in possible information disclosure. This flaw affects versions of libslirp before 4.3.1.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-125
Published	2020-07-09
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: canonical · debian · libslirp project · opensuse · redhat

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-07-09 16:15 UTCPublished CVE record published
2026-06-17 02:48 UTCUpdated Record last modified

libslirp project libslirp UPGRADE

Affected: < 4.3.1

Fixed in: 4.3.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libslirp || rpm -q libslirp || libslirp --version

2. UPGRADE to 4.3.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libslirp

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libslirp

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

redhat openstack DOWNGRADE

Affected: 13

Fixed in: no fixed release known

Safe to downgrade to: a release before 13

1. Check installed version

apt-cache policy openstack || rpm -q openstack || openstack --version

2. No fixed release: DOWNGRADE to a release before 13 (Debian / Ubuntu)

apt-cache madison openstack sudo apt install openstack=<VERSION_BEFORE_13> sudo apt-mark hold openstack

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list openstack sudo dnf downgrade openstack-<VERSION_BEFORE_13> sudo dnf versionlock add openstack

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

redhat enterprise linux MITIGATE

Affected: 7.0 · 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

canonical ubuntu linux MITIGATE

Affected: 16.04 · 18.04 · 20.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 16.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

debian debian linux MITIGATE

Affected: 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

opensuse leap MITIGATE

Affected: 15.0 · 15.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-10756?

libslirp: upgrade to 4.3.1; openstack: downgrade or apply the listed mitigation; enterprise linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-10756 being exploited?

CVE-2020-10756 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-10756 affect?

CVE-2020-10756 affects libslirp, openstack, enterprise linux. Severity is medium (CVSS 6.5). An out-of-bounds read vulnerability was found in the SLiRP networking implementation of the QEMU emulator. This flaw occurs in the icmp6_send_echoreply() routine while replying to an ICMP echo request, also known as ping. This flaw allows a

How urgent is CVE-2020-10756?

Priority 39/100. On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities · QEMU vulnerabilities · OpenStack vulnerabilities

Related CVEs

CVE-2021-3595 LOW 3.8 UPGRADE MITIGATE An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU
CVE-2021-3594 LOW 3.8 UPGRADE MITIGATE An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU
CVE-2021-3593 LOW 3.8 UPGRADE MITIGATE An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU
CVE-2021-3592 LOW 3.8 UPGRADE MITIGATE An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU
CVE-2020-8608 MEDIUM 5.6 DOWNGRADE MITIGATE In libslirp 4.1.0, as used in QEMU 4.2.0, tcp_subr.c misuses snprintf return values, leading to a buffer overf

References

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