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CVE-2018-16881: A denial of service vulnerability was found in rsyslog in the imptcp module

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This month
HIGH 7.5REMOTEWATCHLISTUPGRADEDOWNGRADEMITIGATE

CVE-2018-16881 is a high-severity flaw (CVSS 7.5) affecting rsyslog, virtualization manager, enterprise linux desktop. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A denial of service vulnerability was found in rsyslog in the imptcp module. An attacker could send a specially crafted message to the imptcp socket, which would cause rsyslog to crash. Versions before 8.27.0 are vulnerable.

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance2.2% (top 17%)
CISA exploited listNo
WeaknessCWE-190
Published2019-01-25
Last modified2026-06-17
Publisher (CNA): Red Hat, Inc. · Vendor: redhat · rsyslog

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

Am I affected?

Timeline

rsyslog rsyslog UPGRADE
Affected: < 8.27.0
Fixed in: 8.27.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy rsyslog || rpm -q rsyslog || rsyslog --version
2. UPGRADE to 8.27.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade rsyslog
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade rsyslog
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
redhat virtualization manager DOWNGRADE
Affected: 4.3
Fixed in: no fixed release known
Safe to downgrade to: a release before 4.3
1. Check installed version
apt-cache policy virtualization-manager || rpm -q virtualization-manager || virtualization-manager --version
2. No fixed release: DOWNGRADE to a release before 4.3 (Debian / Ubuntu)
apt-cache madison virtualization-manager sudo apt install virtualization-manager=<VERSION_BEFORE_4.3> sudo apt-mark hold virtualization-manager
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list virtualization-manager sudo dnf downgrade virtualization-manager-<VERSION_BEFORE_4.3> sudo dnf versionlock add virtualization-manager
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 desktop MITIGATE
Affected: 7.0
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.
redhat enterprise linux for ibm z systems MITIGATE
Affected: 7.0
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.
redhat enterprise linux for power big endian MITIGATE
Affected: 7.0
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.
redhat enterprise linux for power little endian MITIGATE
Affected: 7.0
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.
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-2018-16881?

rsyslog: upgrade to 8.27.0; virtualization manager: downgrade or apply the listed mitigation; enterprise linux desktop: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-16881 being exploited?

CVE-2018-16881 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-2018-16881 affect?

CVE-2018-16881 affects rsyslog, virtualization manager, enterprise linux desktop. Severity is high (CVSS 7.5). A denial of service vulnerability was found in rsyslog in the imptcp module. An attacker could send a specially crafted message to the imptcp socket, which would cause rsyslog to crash. Versions before 8.27.0 are vulnerable.

How urgent is CVE-2018-16881?

Priority 57/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Related CVEs

References

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