CVE-2024-53991 in Discourse
Summary
by MITRE • 12/19/2024
Discourse is an open source platform for community discussion. This vulnerability only impacts Discourse instances configured to use `FileStore::LocalStore` which means uploads and backups are stored locally on disk. If an attacker knows the name of the Discourse backup file, the attacker can trick nginx into sending the Discourse backup file with a well crafted request. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. Users are advised to upgrade. Users unable to upgrade can either 1. Download all local backups on to another storage device, disable the `enable_backups` site setting and delete all backups until the site has been upgraded to pull in the fix. Or 2. Change the `backup_location` site setting to `s3` so that backups are stored and downloaded directly from S3.
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Analysis
by VulDB Data Team • 08/26/2025
The vulnerability identified as CVE-2024-53991 affects Discourse, an open source community discussion platform, specifically targeting instances configured with FileStore::LocalStore for backup and upload storage. This configuration stores all backup files and uploaded content directly on the local filesystem rather than utilizing cloud storage solutions. The flaw represents a significant security weakness that could allow unauthorized access to sensitive backup data when proper authentication controls are bypassed through crafted HTTP requests.
The technical exploitation of this vulnerability relies on the attacker's ability to predict or discover the filename of Discourse backup files stored locally on the server. When an attacker knows the specific backup file name, they can manipulate nginx web server configurations to serve these files with maliciously crafted requests that bypass normal access controls. This occurs because the local file storage implementation does not properly validate or restrict access to backup files, allowing direct file retrieval through the web server interface. The vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-200, which covers exposure of sensitive information.
The operational impact of this vulnerability extends beyond simple data exposure, potentially compromising the integrity and confidentiality of entire community discussion platforms. Attackers could gain access to complete backup archives containing user data, discussion history, and potentially sensitive information that would normally be protected within the platform's security boundaries. This threat is particularly concerning for organizations relying on Discourse for sensitive community discussions or those handling regulated data. The vulnerability creates a persistent risk that remains active until properly patched, as it does not require authentication to exploit once the backup filename is known.
Organizations affected by this vulnerability should immediately implement the recommended mitigation strategies. The primary solution involves upgrading to the latest stable, beta, or tests-passed versions of Discourse where the issue has been patched. For those unable to perform immediate upgrades, two alternative approaches are available. The first approach requires downloading all existing local backups to secure storage, disabling the backup functionality through the enable_backups site setting, and deleting all local backup files until the system can be properly updated. This method effectively removes the attack surface by eliminating local backup storage. The second mitigation strategy involves changing the backup_location site setting to S3, which moves backup storage and retrieval operations to AWS S3 infrastructure where proper access controls and authentication mechanisms are implemented. This approach follows ATT&CK technique T1566, which involves credential access through the exploitation of weak or default credentials, by moving sensitive data storage away from vulnerable local filesystem configurations. The recommended mitigation approach should be implemented as a temporary solution until full system upgrades can be completed.