CVE-2013-0238: The try_parse_v4_netmask function in hostmask.c in IRCD-Hybrid before 8.0.6 does not properly validate masks,

Q: How do I fix CVE-2013-0238?

ircd-hybrid: upgrade to newer than 8.0.5. Exact commands for each OS are on this page.

Q: Is CVE-2013-0238 being exploited?

CVE-2013-0238 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-2013-0238 affect?

CVE-2013-0238 affects ircd-hybrid. Severity is medium (CVSS 5.0). The try_parse_v4_netmask function in hostmask.c in IRCD-Hybrid before 8.0.6 does not properly validate masks, which allows remote attackers to cause a denial of service (crash) via a mask that causes a negative number to be parsed.

Q: How urgent is CVE-2013-0238?

Priority 46/100. EPSS top 4%: very likely to be exploited; Public exploit reference

This week

MEDIUM 5.0UPGRADE

CVE-2013-0238 is a medium-severity flaw (CVSS 5.0) affecting ircd-hybrid. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The try_parse_v4_netmask function in hostmask.c in IRCD-Hybrid before 8.0.6 does not properly validate masks, which allows remote attackers to cause a denial of service (crash) via a mask that causes a negative number to be parsed.

Why this priority

EPSS top 4%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	10.0% (top 4%)
CISA exploited list	No
Weakness	CWE-20
Published	2013-02-13
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: ircd-hybrid

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2013-02-13 01:55 UTCPublished CVE record published
2026-06-16 23:49 UTCUpdated Record last modified

ircd-hybrid ircd-hybrid UPGRADE

Affected: <= 8.0.5 · 7.2.0 · 7.2.1 · 7.2.2 · 7.2.3 · 7.3.0 · 7.3.0 rc1 · 7.3.1

Fixed in: newer than 8.0.5

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ircd-hybrid || rpm -q ircd-hybrid || ircd-hybrid --version

2. UPGRADE to newer than 8.0.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ircd-hybrid

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ircd-hybrid

Note

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

Public exploits and detection

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

Exploit-DB: ircd-hybrid 8.0.5 - Denial of Service

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-2013-0238?

ircd-hybrid: upgrade to newer than 8.0.5. Exact commands for each OS are on this page.

Is CVE-2013-0238 being exploited?

CVE-2013-0238 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-2013-0238 affect?

CVE-2013-0238 affects ircd-hybrid. Severity is medium (CVSS 5.0). The try_parse_v4_netmask function in hostmask.c in IRCD-Hybrid before 8.0.6 does not properly validate masks, which allows remote attackers to cause a denial of service (crash) via a mask that causes a negative number to be parsed.

How urgent is CVE-2013-0238?

Priority 46/100. EPSS top 4%: very likely to be exploited; Public exploit reference

References

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