CVE-2018-20177: rdesktop versions up to and including v1.8.3 contain an Integer Overflow that leads to a Heap-Based Buffer Ove

Q: How do I fix CVE-2018-20177?

rdesktop: upgrade to newer than 1.8.3; debian linux: mitigate or apply the listed mitigation; backports: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2018-20177 being exploited?

CVE-2018-20177 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2018-20177 affect?

CVE-2018-20177 affects rdesktop, debian linux, backports. Severity is critical (CVSS 9.8). rdesktop versions up to and including v1.8.3 contain an Integer Overflow that leads to a Heap-Based Buffer Overflow in the function rdp_in_unistr() and results in memory corruption and possibly even a remote code execution.

Q: How urgent is CVE-2018-20177?

Priority 73/100. Critical severity; EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2018-20177 is a critical-severity flaw (CVSS 9.8) affecting rdesktop, debian linux, backports. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

rdesktop versions up to and including v1.8.3 contain an Integer Overflow that leads to a Heap-Based Buffer Overflow in the function rdp_in_unistr() and results in memory corruption and possibly even a remote code execution.

Why this priority

Critical severity
EPSS top 5%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	7.9% (top 5%)
CISA exploited list	No
Weakness	CWE-190, CWE-787
Published	2019-03-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · opensuse · rdesktop

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

Am I affected?

Timeline

2019-03-15 18:29 UTCPublished CVE record published
2026-06-17 01:52 UTCUpdated Record last modified

rdesktop rdesktop UPGRADE

Affected: <= 1.8.3

Fixed in: newer than 1.8.3

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 1.8.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade rdesktop

Note

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

debian debian linux MITIGATE

Affected: 8.0 · 9.0

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 backports MITIGATE

Affected: sle-15 sp1

Fixed in: no fixed release known

Safe to downgrade to: a release before sle-15

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · root · FIXED · 6.40.04-7.fc46 · FEDORA-2026-7329868400 · source

sudo dnf upgrade --advisory=FEDORA-2026-7329868400

Ubuntu 22.04 · rdesktop · NOT AFFECTED

Ubuntu 20.04 · rdesktop · NOT AFFECTED

Ubuntu 24.04 · rdesktop · NOT AFFECTED

Ubuntu 24.10 · rdesktop · NOT AFFECTED

Ubuntu 25.04 · rdesktop · NOT AFFECTED

Debian 12 · rdesktop · FIXED · 1.8.4-1

sudo apt update && sudo apt install --only-upgrade rdesktop dpkg --compare-versions "$(dpkg-query -W -f='${Version}' rdesktop)" ge "1.8.4-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · rdesktop · FIXED · 1.8.4-1

sudo apt update && sudo apt install --only-upgrade rdesktop dpkg --compare-versions "$(dpkg-query -W -f='${Version}' rdesktop)" ge "1.8.4-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 5 · rdesktop · DEFERRED

RHEL 6 · rdesktop · DEFERRED

Alpine 3.20 · rdesktop · FIXED · rdesktop-1.8.6-r0

apk add --upgrade rdesktop apk info -v rdesktop

Alpine 3.21 · rdesktop · FIXED · rdesktop-1.8.6-r0

apk add --upgrade rdesktop apk info -v rdesktop

Alpine 3.22 · rdesktop · FIXED · rdesktop-1.8.6-r0

apk add --upgrade rdesktop apk info -v rdesktop

Alpine 3.23 · rdesktop · FIXED · rdesktop-1.8.6-r0

apk add --upgrade rdesktop apk info -v rdesktop

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: research.checkpoint.com/reverse-rdp-attack-code-execution-on-rdp-clients/

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-2018-20177?

rdesktop: upgrade to newer than 1.8.3; debian linux: mitigate or apply the listed mitigation; backports: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-20177 being exploited?

CVE-2018-20177 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-2018-20177 affect?

CVE-2018-20177 affects rdesktop, debian linux, backports. Severity is critical (CVSS 9.8). rdesktop versions up to and including v1.8.3 contain an Integer Overflow that leads to a Heap-Based Buffer Overflow in the function rdp_in_unistr() and results in memory corruption and possibly even a remote code execution.

How urgent is CVE-2018-20177?

Priority 73/100. Critical severity; EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · WinRM and RDP vulnerabilities

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References

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