CVE-2022-4639: A vulnerability, which was classified as critical, has been found in sslh

This month

MEDIUM 5.6REMOTEDOWNGRADE

CVE-2022-4639 is a medium-severity flaw (CVSS 5.6) affecting sslh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability, which was classified as critical, has been found in sslh. This issue affects the function hexdump of the file probe.c of the component Packet Dumping Handler. The manipulation of the argument msg_info leads to format string. The attack may be initiated remotely. The name of the patch is b19f8a6046b080e4c2e28354a58556bb26040c6f. It is recommended to apply a patch to fix this issue. The identifier VDB-216497 was assigned to this vu

Why this priority

Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	5.6 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-119, CWE-134
Published	2022-12-21
Last modified	2026-06-17

Publisher (CNA): VulDB · Vendor: sslh project

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

Am I affected?

Timeline

2022-12-21 22:15 UTCPublished CVE record published
2026-06-17 05:21 UTCUpdated Record last modified

sslh project sslh DOWNGRADE

Affected: 2.0 rc1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

apt-cache madison sslh sudo apt install sslh=<VERSION_BEFORE_2.0> sudo apt-mark hold sslh

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

dnf --showduplicates list sslh sudo dnf downgrade sslh-<VERSION_BEFORE_2.0> sudo dnf versionlock add sslh

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-2022-4639?

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

Is CVE-2022-4639 being exploited?

CVE-2022-4639 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-2022-4639 affect?

CVE-2022-4639 affects sslh. Severity is medium (CVSS 5.6). A vulnerability, which was classified as critical, has been found in sslh. This issue affects the function hexdump of the file probe.c of the component Packet Dumping Handler. The manipulation of the argument msg_info leads to format string

How urgent is CVE-2022-4639?

Priority 40/100. Remotely exploitable, no login, no user action

References

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