CVE-2016-6903: lshell 0.9.16 allows remote authenticated users to break out of a limited shell and execute arbitrary commands

This week

CRITICAL 9.9WATCHLISTDOWNGRADE

CVE-2016-6903 is a critical-severity flaw (CVSS 9.9) affecting lshell. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

lshell 0.9.16 allows remote authenticated users to break out of a limited shell and execute arbitrary commands.

Why this priority

Critical severity
EPSS top 8%: very likely to be exploited
On your watchlist

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

Risk facts

CVSS score	9.9 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	5.0% (top 8%)
CISA exploited list	No
Weakness	CWE-264
Published	2017-04-24
Last modified	2026-06-17

Publisher (CNA): Debian GNU/Linux · Vendor: lshell project

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

Am I affected?

Timeline

2017-04-24 19:59 UTCPublished CVE record published
2026-06-17 00:51 UTCUpdated Record last modified

lshell project lshell DOWNGRADE

Affected: 0.9.16

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9.16

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.9.16 (Debian / Ubuntu)

apt-cache madison lshell sudo apt install lshell=<VERSION_BEFORE_0.9.16> sudo apt-mark hold lshell

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

dnf --showduplicates list lshell sudo dnf downgrade lshell-<VERSION_BEFORE_0.9.16> sudo dnf versionlock add lshell

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-2016-6903?

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

Is CVE-2016-6903 being exploited?

CVE-2016-6903 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-2016-6903 affect?

CVE-2016-6903 affects lshell. Severity is critical (CVSS 9.9). lshell 0.9.16 allows remote authenticated users to break out of a limited shell and execute arbitrary commands.

How urgent is CVE-2016-6903?

Priority 63/100. Critical severity; EPSS top 8%: very likely to be exploited; On your watchlist

Related CVEs

CVE-2016-6902 CRITICAL 9.9 DOWNGRADE lshell 0.9.16 allows remote authenticated users to break out of a limited shell and execute arbitrary commands

References

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