CVE-2025-57682 is a directory traversal vulnerability identified in Papermark version 0.20.0 and earlier. This vulnerability allows authenticated attackers to exploit the "POST /api/file/s3/get-presigned-get-url-proxy" API endpoint to retrieve arbitrary files from an Amazon S3 bucket via its CloudFront distribution. The vulnerability is categorized under CWE-22, which relates to improper restriction of file paths, enabling attackers to traverse directories and access files outside the intended scope. The attack vector is network-based (AV:N), requiring low attack complexity (AC:L) but does require the attacker to have some level of privileges (PR:L), specifically authenticated access. No user interaction is needed (UI:N), and the vulnerability impacts confidentiality (C:H) without affecting integrity or availability. The CVSS v3.1 base score is 6.5, indicating a medium severity level. The vulnerability does not currently have known exploits in the wild, and no patches have been linked yet. The core technical issue is that the API does not properly validate or sanitize the file path input, allowing traversal sequences (e.g., "../") to access files beyond the intended directory within the S3 bucket. Since the S3 bucket is exposed through CloudFront, this can lead to unauthorized disclosure of sensitive files stored in the bucket, potentially including configuration files, credentials, or other sensitive data. The requirement for authentication limits the attack surface to users with some level of access, but the impact on confidentiality remains significant given the potential sensitivity of the files accessible via this flaw.

For European organizations using Papermark 0.20.0 or earlier, this vulnerability poses a significant risk to data confidentiality. Many organizations rely on cloud storage solutions like Amazon S3 for storing sensitive documents, backups, or configuration files. An attacker with authenticated access could exploit this vulnerability to exfiltrate sensitive information, potentially leading to data breaches, regulatory non-compliance (e.g., GDPR violations), and reputational damage. The exposure of sensitive files could also facilitate further attacks, such as credential theft or lateral movement within the organization’s infrastructure. Since the vulnerability does not affect integrity or availability, the primary concern is unauthorized data disclosure. European organizations in sectors such as finance, healthcare, government, and critical infrastructure, which often handle highly sensitive data, would be particularly impacted. Additionally, the use of CloudFront as a CDN in front of the S3 bucket means that the attack can be executed remotely over the internet, increasing the risk of exploitation if authentication credentials are compromised or weak.

To mitigate this vulnerability, organizations should first verify if they are using Papermark version 0.20.0 or earlier and assess their exposure to the vulnerable API endpoint. Immediate steps include: 1) Restricting access to the affected API endpoint to only trusted and necessary users, implementing strict authentication and authorization controls. 2) Implementing input validation and sanitization on the server side to prevent directory traversal sequences in file path parameters. 3) Reviewing and tightening S3 bucket policies to limit file access strictly to necessary files and users, including using least privilege principles. 4) Monitoring access logs for unusual or unauthorized attempts to access files via the API or CloudFront distribution. 5) Applying any available patches or updates from Papermark vendors as soon as they are released. 6) If patches are not yet available, consider temporarily disabling or restricting the vulnerable API endpoint to prevent exploitation. 7) Employing Web Application Firewalls (WAF) with rules to detect and block directory traversal attempts targeting the API. 8) Conducting security audits and penetration testing focused on API endpoints and cloud storage access controls to identify and remediate similar issues proactively.