CyberSecBulletin
CVE-2024-1874NVD status: Modified

PHP: Improper Encoding or Escaping of Output

Published Updated By the CyberSecBulletin desk

CVE-2024-1874 is a critical-severity improper encoding or escaping of output vulnerability in PHP from PHP Group, with a CVSS 3.1 base score of 9.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 8.1.28, 8.2.18, 8.3.5 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 32.8% chance of exploitation within 30 days, which is in the top 1.62% of all scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update PHP to 8.1.28 or 8.2.18 or 8.3.5, whichever matches your release line, or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
PHP GroupPHP8.1.* up to, but not including, 8.1.28; 8.2.* up to, but not including, 8.2.18; 8.3.* up to, but not including, 8.3.5; 8.1.0; 8.2.0; 8.3.08.1.28, 8.2.18, 8.3.5
Fedora ProjectFedora39; 40Not 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
NoneNo account or login is needed.
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
LowPerformance or availability is reduced.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L. Scored by CNA (php.net).

Official description

In PHP versions 8.1.* before 8.1.28, 8.2.* before 8.2.18, 8.3.* before 8.3.5, when using proc_open() command with array syntax, due to insufficient escaping, if the arguments of the executed command are controlled by a malicious user, the user can supply arguments that would execute arbitrary commands in Windows shell.

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

The underlying weakness: Improper Encoding or Escaping of Output

The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.

How developers prevent this class of flaw

  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
  • If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
  • Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.

More Improper Encoding or Escaping of Output vulnerabilities (CWE-116)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Other vulnerabilities in PHP

All PHP vulnerabilities

Recent Improper Encoding or Escaping of Output vulnerabilities

Spotted an error? Tell us.