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PHPApplication

CVE-2016-4073

CRITICAL · 9.8 CVSS v3.0 Published 2016-05-20
Fix available
A fix is available. Upgrade to after 10.11.3 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

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 · unedited
Multiple integer overflows in the mbfl_strcut function in ext/mbstring/libmbfl/mbfl/mbfilter.c in PHP before 5.5.34, 5.6.x before 5.6.20, and 7.x before 7.0.5 allow remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted mb_strcut call.

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
How this class of weakness works · CWE-119

The program reads or writes outside the bounds of an allocated buffer, corrupting adjacent memory. With crafted input an attacker can overwrite control data and, with effort, redirect execution to their own code. Remediation ranges from bounds checking and safe library functions to compiler mitigations, usually alongside a careful audit of the surrounding code.

General guidance for the memory buffer bounds error class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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
Affected:= 5.5.0= 5.5.1= 5.5.2= 5.5.3= 5.5.4= 5.5.5= 5.5.6= 5.5.7= 5.5.8= 5.5.9= 5.5.10= 5.5.11
Mac Os XOperating system
Affected:<= 10.11.3

CVSS 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:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 · scoped
Upgrade available Upgrade to a release after 10.11.3
Recommended fix High confidence

PHP 5.5.34, PHP 5.6.20, or PHP 7.0.5 (or later in respective branches)

  1. 1. Check current PHP version by running 'php -v' or 'phpinfo()'
  2. 2. For Linux/Unix systems using package managers: update your package index (e.g., 'apt-get update' for Debian/Ubuntu, 'yum update' for RHEL/CentOS)
  3. 3. Install the updated PHP package. For apt: 'apt-get install php5' or 'apt-get install php7.0' depending on desired branch. For yum: 'yum update php'
  4. 4. For macOS with Homebrew: run 'brew update' then 'brew upgrade php'
  5. 5. For macOS with MacPorts: run 'sudo port selfupdate' then 'sudo port upgrade php56' or 'sudo port upgrade php70'
  6. 6. Restart any running PHP processes or web servers (Apache, Nginx, PHP-FPM) to load the new version
  7. 7. Verify the fix by running 'php -v' to confirm the version is 5.5.34, 5.6.20, 7.0.5 or higher, or by checking phpinfo() for the mbstring version
Caveat PHP 7.x has breaking changes from PHP 5.x. If upgrading from PHP 5.5/5.6 to PHP 7.x, review the migration guide at https://www.php.net/manual/en/migration70.php for incompatible changes. Upgrading within the same major version (e.g., 5.5.x to 5.5.34) should have minimal breaking changes.

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-4073 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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