CyberSecBulletin
CVE-2022-31626NVD status: Modified

PHP: Buffer Copy without Checking Size of Input

Published Updated By the CyberSecBulletin desk

CVE-2022-31626 is a high-severity buffer copy without checking size of input vulnerability in PHP from PHP Group, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 7.4.30, 8.0.20, 8.1.7 as the first without the flaw, so updating PHP to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 58.1% chance of exploitation within 30 days, which is in the top 0.9% of all scored CVEs.

Patch now

Exploitation in the next 30 days is more likely than not, according to EPSS.

What to do

  1. Update PHP to 7.4.30 or 8.0.20 or 8.1.7, whichever matches your release line, or a later version.
  2. Read the advisory on bugs.php.net for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
PHP GroupPHP7.4.X up to, but not including, 7.4.30; 8.0.X up to, but not including, 8.0.20; 8.1.X up to, but not including, 8.1.77.4.30, 8.0.20, 8.1.7
DebianDebian Linux10.0; 11.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighCNA (php.net)
CVSS 3.18.8HighNVD
CVSS 2.06.0MediumNVD

Official description

In PHP versions 7.4.x below 7.4.30, 8.0.x below 8.0.20, and 8.1.x below 8.1.7, when pdo_mysql extension with mysqlnd driver, if the third party is allowed to supply host to connect to and the password for the connection, password of excessive length can trigger a buffer overflow in PHP, which can lead to a remote code execution vulnerability.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Buffer Copy without Checking Size of Input

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Advisories

Third-party and government advisories

Other vulnerabilities in PHP

All PHP vulnerabilities

Recent Buffer Copy without Checking Size of Input vulnerabilities

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