PHP 'unserialize()' Stack Buffer Overflow Vulnerability



Date Discovered

September 16, 2019


PHP is prone to a remote stack-based buffer-overflow because it fails to adequately bounds-check user-supplied data before copying it into an insufficiently sized buffer. An attacker can exploit this issue to cause a denial-of-service condition. Due to the nature of this issue, code execution may be possible but this has not been confirmed.

Technologies Affected

  • PHP PHP 7.3.0
  • PHP PHP 7.3.1
  • PHP PHP 7.3.10
  • PHP PHP 7.3.11
  • PHP PHP 7.3.2
  • PHP PHP 7.3.3
  • PHP PHP 7.3.4
  • PHP PHP 7.3.5
  • PHP PHP 7.3.6
  • PHP PHP 7.3.7
  • PHP PHP 7.3.8
  • PHP PHP 7.3.9


Permit local access for trusted individuals only. Where possible, use restricted environments and restricted shells.
Allow only trusted individuals to have user accounts and local access to the resources.

Run all software as a nonprivileged user with minimal access rights.
To limit the potential damage that a successful exploit may achieve, run all nonadministrative software as a regular user with the least amount of privileges required to successfully operate.

Do not accept or execute files from untrusted or unknown sources.
To reduce the likelihood of successful exploits, never handle files that originate from unfamiliar or untrusted sources.

Implement multiple redundant layers of security.
Various memory-protection schemes (such as nonexecutable and randomly mapped memory segments) may hinder an attacker's ability to exploit this vulnerability to execute arbitrary code.

Updates are available. Please see the references or vendor advisory for more information.



The vendor reported this issue.

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