CVE-2023-3823: Security issue with external entity loading in XML without enabling it

Vulnerability summary

CVE-2023-3823 is a high (CVSS 8.6) vulnerability in debian debian_linux. EPSS estimates a 1.64% chance of exploitation in the next 30 days, higher than 76.3% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 11-08-2023
   PublishedVulnerability first disclosed.
2. 13-02-2025
   Last modifiedVulnerability information updated.

Description

In PHP versions 8.0.* before 8.0.30, 8.1.* before 8.1.22, and 8.2.* before 8.2.8 various XML functions rely on libxml global state to track configuration variables, like whether external entities are loaded. This state is assumed to be unchanged unless the user explicitly changes it by calling appropriate function. However, since the state is process-global, other modules - such as ImageMagick - may also use this library within the same process, and change that global state for their internal purposes, and leave it in a state where external entities loading is enabled. This can lead to the situation where external XML is parsed with external entities loaded, which can lead to disclosure of any local files accessible to PHP. This vulnerable state may persist in the same process across many requests, until the process is shut down.

• CWE-611Improper Restriction of XML External Entity ReferenceThe product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.