CVE-2020-26100
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedchsh in cPanel before 88.0.3 allows a Jailshell escape (SEC-497).
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThe chsh command in cPanel before version 88.0.3 contains a vulnerability that allows users in a Jailshell environment to escape the jail and potentially gain elevated privileges. The chsh utility is intended to allow users to change their login shell, but improper validation in the jailed context enables privilege escalation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 88.0.3CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check the installed cPanel versionRun the command: /usr/local/cpanel/cpanel -V or check WHM root access > Server Information > cPanel versionAffected if The version number is lower than 88.0.3
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Identify users assigned to JailshellCheck the /etc/passwd file for users with /usr/local/cpanel/bin/jailshell or /bin/jailshell as their login shell, or use the command: grep jailshell /etc/passwdAffected if Any user accounts are configured to use Jailshell as their login shell
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Verify the chsh utility is accessible to usersAs a user in Jailshell, attempt to run the chsh command or check if it exists in the user's PATH using: which chsh or ls -la /usr/bin/chshAffected if The chsh command is executable by jailshell users and not restricted or wrapped properly
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Check for unauthorized shell changesReview /etc/shadow or audit logs for unexpected changes to user shells, or run: grep -E '^[^:]+:[^:]+:[0-9]+:[0-9]+:[^:]+:[^:]+:/' /etc/passwd to list shells currently in useAffected if Users have shells outside the expected /bin/jailshell or documented legitimate shells
A system is affected if running cPanel version lower than 88.0.3 AND has users assigned to Jailshell with access to the chsh command.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped88.0.3
Upgrade cPanel to version 88.0.3 or later to obtain the security patch for SEC-497. Additionally, review user shell assignments and monitor for any unauthorized access attempts.
cPanel 88.0.3 or later
- Upgrade cPanel to version 88.0.3 or later using the cPanel update mechanism
- Verify the upgrade completed successfully
- Confirm the chsh command is now restricted and cannot be used to escape Jailshell
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-26100 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-26100 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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