CVE-2026-23907 is a path traversal vulnerability classified under CWE-22 found in the ExtractEmbeddedFiles example of the Apache PDFBox library, specifically in versions 2.0.24 through 2.0.36 and 3.0.0 through 3.0.7. The vulnerability occurs because the example code appends the filename retrieved from PDComplexFileSpecification.getFilename() directly to the extraction path without sanitization or validation. This allows an attacker to craft malicious PDF files containing embedded files with filenames that include directory traversal sequences (e.g., '../'), enabling extraction of files outside the intended directory. Such behavior can lead to arbitrary file writes on the host system, potentially overwriting critical files or placing malicious payloads in sensitive locations. The vulnerability is limited to users who have copied the example code into their production environments without implementing proper path validation. The Apache PDFBox team has addressed this by modifying the example to convert both the initial extraction path and the target extraction path to canonical forms and verifying that the extraction path is contained within the initial directory, preventing traversal. Documentation has also been updated to warn users. No CVSS score has been assigned, and no known exploits have been reported in the wild. The vulnerability requires an attacker to supply a crafted PDF file and for the vulnerable extraction code to be used in a context where such files are processed, which limits the attack surface. However, the risk remains significant for organizations that use the example code as-is in production.

The primary impact of this vulnerability is the potential for arbitrary file write outside the intended extraction directory, which can lead to several security issues. An attacker could overwrite critical system or application files, potentially leading to denial of service, privilege escalation, or remote code execution if the overwritten files are executable or configuration files. The confidentiality and integrity of the system could be compromised if sensitive files are replaced or malicious files are planted. Since the vulnerability exists in example code, the impact depends heavily on whether organizations have incorporated this example into their production workflows without additional safeguards. If exploited, this could affect any system processing untrusted PDF files with embedded content using the vulnerable code, including document management systems, automated processing pipelines, or web applications. The lack of known exploits suggests limited current active exploitation, but the ease of exploitation through crafted PDFs and the widespread use of Apache PDFBox in Java applications worldwide means the threat should not be underestimated. The vulnerability could disrupt business operations and damage organizational reputation if exploited.

Organizations should immediately review their use of Apache PDFBox, particularly any custom code derived from the ExtractEmbeddedFiles example. They should ensure that extraction paths are properly sanitized and validated by converting paths to their canonical forms and verifying that the extraction path is contained within the intended directory, as recommended by the Apache PDFBox project. Avoid using example code directly in production without security review. Upgrade to Apache PDFBox versions later than 2.0.36 or 3.0.7 where the example has been corrected. Implement strict input validation and sandboxing when processing untrusted PDF files, including limiting file system permissions of the extraction process to prevent unauthorized file writes. Monitor logs for suspicious file extraction activities and consider employing runtime application self-protection (RASP) or endpoint detection to detect anomalous file system operations. Educate developers on secure coding practices to prevent path traversal vulnerabilities. If upgrading is not immediately possible, apply manual patches to the extraction logic to enforce path validation. Finally, restrict the acceptance of PDF files from untrusted sources or implement additional scanning before processing.