CVE-2020-8445: In OSSEC-HIDS 2.7 through 3.5.0, the OS_CleanMSG function in ossec-analysisd doesn't remove or encode terminal

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CRITICAL 9.8REMOTEUPGRADE

CVE-2020-8445 is a critical-severity flaw (CVSS 9.8) affecting ossec. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In OSSEC-HIDS 2.7 through 3.5.0, the OS_CleanMSG function in ossec-analysisd doesn't remove or encode terminal control characters or newlines from processed log messages. In many cases, those characters are later logged. Because newlines (\n) are permitted in messages processed by ossec-analysisd, it may be possible to inject nested events into the ossec log. Use of terminal control characters may allow obfuscating events or executing commands wh

Why this priority

Critical severity
Remotely exploitable, no login, no user action

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	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-20
Published	2020-01-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: ossec

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

Am I affected?

Timeline

2020-01-30 01:15 UTCPublished CVE record published
2026-06-17 03:26 UTCUpdated Record last modified

ossec ossec UPGRADE

Affected: >= 2.7 and <= 3.5.0

Fixed in: newer than 3.5.0

Safe to downgrade to: a release before 2.7

1. Check installed version

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

2. UPGRADE to newer than 3.5.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ossec

Note

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

3. If no update is available yet, DOWNGRADE to a release before 2.7 (Debian / Ubuntu)

apt-cache madison ossec sudo apt install ossec=<VERSION_BEFORE_2.7> sudo apt-mark hold ossec

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ossec sudo dnf downgrade ossec-<VERSION_BEFORE_2.7> sudo dnf versionlock add ossec

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.

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-2020-8445?

ossec: upgrade to newer than 3.5.0. Exact commands for each OS are on this page.

Is CVE-2020-8445 being exploited?

CVE-2020-8445 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-2020-8445 affect?

CVE-2020-8445 affects ossec. Severity is critical (CVSS 9.8). In OSSEC-HIDS 2.7 through 3.5.0, the OS_CleanMSG function in ossec-analysisd doesn't remove or encode terminal control characters or newlines from processed log messages. In many cases, those characters are later logged. Because newlines (\

How urgent is CVE-2020-8445?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-28040 HIGH 7.5 DOWNGRADE An issue was discovered in OSSEC 3.6.0
CVE-2020-8448 MEDIUM 5.5 UPGRADE In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulner
CVE-2020-8447 CRITICAL 9.8 UPGRADE In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulner
CVE-2020-8446 MEDIUM 5.5 UPGRADE In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulner
CVE-2020-8444 CRITICAL 9.8 UPGRADE In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulner

References

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