CVE-2020-8608: In libslirp 4.1.0, as used in QEMU 4.2.0, tcp_subr.c misuses snprintf return values, leading to a buffer overf

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MEDIUM 5.6REMOTEWATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2020-8608 is a medium-severity flaw (CVSS 5.6) affecting libslirp, debian linux, leap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In libslirp 4.1.0, as used in QEMU 4.2.0, tcp_subr.c misuses snprintf return values, leading to a buffer overflow in later code.

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.6 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-120
Published	2020-02-06
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · libslirp project · opensuse

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

Am I affected?

Timeline

2020-02-06 17:15 UTCPublished CVE record published
2026-06-17 03:26 UTCUpdated Record last modified

libslirp project libslirp DOWNGRADE

Affected: 4.1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.1.0 (Debian / Ubuntu)

apt-cache madison libslirp sudo apt install libslirp=<VERSION_BEFORE_4.1.0> sudo apt-mark hold libslirp

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

dnf --showduplicates list libslirp sudo dnf downgrade libslirp-<VERSION_BEFORE_4.1.0> sudo dnf versionlock add libslirp

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.

debian debian linux MITIGATE

Affected: 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

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: 15.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.1

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-2020-8608?

libslirp: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation; leap: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-8608 being exploited?

CVE-2020-8608 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-2020-8608 affect?

CVE-2020-8608 affects libslirp, debian linux, leap. Severity is medium (CVSS 5.6). In libslirp 4.1.0, as used in QEMU 4.2.0, tcp_subr.c misuses snprintf return values, leading to a buffer overflow in later code.

How urgent is CVE-2020-8608?

Priority 51/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · QEMU 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-2020-7211 HIGH 7.5 DOWNGRADE DOWNGRADE tftp.c in libslirp 4.1.0, as used in QEMU 4.2.0, does not prevent ..\ directory traversal on Windows.

References

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