CVE-2016-2233: Stack-based buffer overflow in the inbound_cap_ls function in common/inbound.c in HexChat 2.10.2 allows remote

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HIGH 7.5REMOTEDOWNGRADE

CVE-2016-2233 is a high-severity flaw (CVSS 7.5) affecting hexchat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Stack-based buffer overflow in the inbound_cap_ls function in common/inbound.c in HexChat 2.10.2 allows remote IRC servers to cause a denial of service (crash) via a large number of options in a CAP LS message.

Why this priority

High severity
EPSS top 2%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	34.1% (top 2%)
CISA exploited list	No
Weakness	CWE-119
Published	2017-01-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: hexchat project

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

Am I affected?

Timeline

2017-01-18 17:59 UTCPublished CVE record published
2026-06-17 00:43 UTCUpdated Record last modified

hexchat project hexchat DOWNGRADE

Affected: 2.10.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.10.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.10.2 (Debian / Ubuntu)

apt-cache madison hexchat sudo apt install hexchat=<VERSION_BEFORE_2.10.2> sudo apt-mark hold hexchat

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

dnf --showduplicates list hexchat sudo dnf downgrade hexchat-<VERSION_BEFORE_2.10.2> sudo dnf versionlock add hexchat

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.

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: Hexchat IRC Client 2.11.0 - CAP LS Handling Buffer Overflow

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-2016-2233?

hexchat: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2016-2233 being exploited?

CVE-2016-2233 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-2016-2233 affect?

CVE-2016-2233 affects hexchat. Severity is high (CVSS 7.5). Stack-based buffer overflow in the inbound_cap_ls function in common/inbound.c in HexChat 2.10.2 allows remote IRC servers to cause a denial of service (crash) via a large number of options in a CAP LS message.

How urgent is CVE-2016-2233?

Priority 61/100. High severity; EPSS top 2%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2016-2087 HIGH 7.4 DOWNGRADE Directory traversal vulnerability in the client in HexChat 2.11.0 allows remote IRC servers to read or modify
CVE-2013-7449 MEDIUM 6.5 MITIGATE MITIGATE The ssl_do_connect function in common/server.c in HexChat before 2.10.2, XChat, and XChat-GNOME does not verif

References

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