CVE-2019-17042: An issue was discovered in Rsyslog v8.1908.0

This week

CRITICAL 9.8REMOTEWATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2019-17042 is a critical-severity flaw (CVSS 9.8) affecting rsyslog, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in Rsyslog v8.1908.0. contrib/pmcisconames/pmcisconames.c has a heap overflow in the parser for Cisco log messages. The parser tries to locate a log message delimiter (in this case, a space or a colon), but fails to account for strings that do not satisfy this constraint. If the string does not match, then the variable lenMsg will reach the value zero and will skip the sanity check that detects invalid log messages. The me

Why this priority

Critical severity
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	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.0% (top 13%)
CISA exploited list	No
Weakness	CWE-20
Published	2019-10-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · fedoraproject · opensuse · rsyslog

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

Am I affected?

Timeline

2019-10-07 16:15 UTCPublished CVE record published
2026-06-17 02:23 UTCUpdated Record last modified

rsyslog rsyslog DOWNGRADE

Affected: 8.1908.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.1908.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 8.1908.0 (Debian / Ubuntu)

apt-cache madison rsyslog sudo apt install rsyslog=<VERSION_BEFORE_8.1908.0> sudo apt-mark hold rsyslog

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

dnf --showduplicates list rsyslog sudo dnf downgrade rsyslog-<VERSION_BEFORE_8.1908.0> sudo dnf versionlock add rsyslog

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.

fedoraproject fedora MITIGATE

Affected: 30 · 31

Fixed in: no fixed release known

Safe to downgrade to: a release before 30

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

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-2019-17042?

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

Is CVE-2019-17042 being exploited?

CVE-2019-17042 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-2019-17042 affect?

CVE-2019-17042 affects rsyslog, fedora, debian linux. Severity is critical (CVSS 9.8). An issue was discovered in Rsyslog v8.1908.0. contrib/pmcisconames/pmcisconames.c has a heap overflow in the parser for Cisco log messages. The parser tries to locate a log message delimiter (in this case, a space or a colon), but fails to

How urgent is CVE-2019-17042?

Priority 66/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · Cisco vulnerabilities

Related CVEs

CVE-2026-19654 HIGH 7.5 UPGRADE MITIGATE A unauthenticated remote peer may lead rsyslogd to crash due to a flaw in the optional imptcp module
CVE-2019-17041 CRITICAL 9.8 DOWNGRADE MITIGATE An issue was discovered in Rsyslog v8.1908.0
CVE-2019-17040 CRITICAL 9.8 DOWNGRADE contrib/pmdb2diag/pmdb2diag.c in Rsyslog v8.1908.0 allows out-of-bounds access because the level length is mis
CVE-2018-16881 HIGH 7.5 UPGRADE DOWNGRADE A denial of service vulnerability was found in rsyslog in the imptcp module
CVE-2017-12588 CRITICAL 9.8 UPGRADE The zmq3 input and output modules in rsyslog before 8.28.0 interpreted description fields as format strings, p

References

← Back to latest CVEs