PHPApplication
CVE-2022-4900
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 · uneditedA vulnerability was found in PHP where setting the environment variable PHP_CLI_SERVER_WORKERS to a large value leads to a heap buffer overflow.
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 confidenceHeap buffer overflow in PHP's built-in CLI server when the PHP_CLI_SERVER_WORKERS environment variable is set to an excessively large value, potentially allowing denial of service or potentially code execution through memory corruption.
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
PHPApplication
< 8.0.22
Software CollectionsApplication
all versions
Enterprise LinuxOperating system
= 6.0= 7.0= 8.0= 9.0CVSS 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
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 installed PHP versionRun 'php -v' to obtain the PHP version numberAffected if The version is less than 8.0.22 (e.g., 8.0.21, 8.0.20, 7.x, etc.)
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Check for PHP_CLI_SERVER_WORKERS environment variableRun 'echo $PHP_CLI_SERVER_WORKERS' or 'env | grep PHP_CLI_SERVER_WORKERS'Affected if The variable is set to a numeric value, particularly any value greater than a few dozen (the exact threshold depends on memory allocation but even moderately large values like 1000+ are risky)
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Identify if PHP CLI server is in useSearch for scripts or commands using 'php -S' (the built-in CLI server), or check for any cron jobs, systemd services, or application startup scripts that invoke 'php -S'Affected if PHP's built-in development server is being invoked (via php -S) in any context such as local development, testing, or automated scripts
You are affected if you run PHP version < 8.0.22 AND have PHP_CLI_SERVER_WORKERS set to a large numeric value AND use the PHP CLI server (php -S), as all three conditions must be met for the vulnerable code path to execute.
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 · scoped8.0.22
Upgrade PHP to a version containing the fix for this vulnerability. Avoid setting PHP_CLI_SERVER_WORKERS to large values until the patch is applied.
PHP 8.0.22 or later (8.1.x or 8.2.x recommended for better security support)
- Check the current PHP version using 'php --version' or 'php -v'
- Identify the package manager used (yum, dnf, apt, etc.) for your system
- Update the package repository metadata
- Upgrade PHP to version 8.0.22 or later using the appropriate package manager (e.g., 'dnf update php' or 'apt-get install php8.0' or similar)
- Verify the PHP version has been updated to 8.0.22 or later using 'php --version'
- Test that critical PHP applications function correctly after the upgrade
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in PHP
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,808.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2022-4900 — 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-2022-4900 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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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