CVE-2019-13455: In Xymon through 4.3.28, a stack-based buffer overflow vulnerability exists in the alert acknowledgment CGI to

Q: How do I fix CVE-2019-13455?

xymon: upgrade to newer than 4.3.28; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2019-13455 being exploited?

CVE-2019-13455 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-2019-13455 affect?

CVE-2019-13455 affects xymon, debian linux. Severity is critical (CVSS 9.8). In Xymon through 4.3.28, a stack-based buffer overflow vulnerability exists in the alert acknowledgment CGI tool because of expansion in acknowledge.c.

Q: How urgent is CVE-2019-13455?

Priority 69/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2019-13455 is a critical-severity flaw (CVSS 9.8) affecting xymon, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Xymon through 4.3.28, a stack-based buffer overflow vulnerability exists in the alert acknowledgment CGI tool because of   expansion in acknowledge.c.

Why this priority

Critical severity
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	2.0% (top 19%)
CISA exploited list	No
Weakness	CWE-787
Published	2019-08-27
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · xymon

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

Am I affected?

Timeline

2019-08-27 17:15 UTCPublished CVE record published
2026-06-17 02:16 UTCUpdated Record last modified

xymon xymon UPGRADE

Affected: <= 4.3.28

Fixed in: newer than 4.3.28

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 4.3.28 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade xymon

Note

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

debian debian linux MITIGATE

Affected: 8.0

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.

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-2019-13455?

xymon: upgrade to newer than 4.3.28; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-13455 being exploited?

CVE-2019-13455 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-2019-13455 affect?

CVE-2019-13455 affects xymon, debian linux. Severity is critical (CVSS 9.8). In Xymon through 4.3.28, a stack-based buffer overflow vulnerability exists in the alert acknowledgment CGI tool because of   expansion in acknowledge.c.

How urgent is CVE-2019-13455?

Priority 69/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2019-13486 CRITICAL 9.8 UPGRADE MITIGATE In Xymon through 4.3.28, a stack-based buffer overflow exists in the status-log viewer component because of &n
CVE-2019-13485 CRITICAL 9.8 UPGRADE MITIGATE In Xymon through 4.3.28, a stack-based buffer overflow vulnerability exists in the history viewer component vi
CVE-2019-13484 CRITICAL 9.8 UPGRADE MITIGATE In Xymon through 4.3.28, a buffer overflow exists in the status-log viewer CGI because of   expansion in
CVE-2019-13452 CRITICAL 9.8 UPGRADE MITIGATE In Xymon through 4.3.28, a buffer overflow vulnerability exists in reportlog.c.
CVE-2019-13451 CRITICAL 9.8 UPGRADE MITIGATE In Xymon through 4.3.28, a buffer overflow vulnerability exists in history.c.

References

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