CVE-2022-24837 in HedgeDoc
Summary
by MITRE • 04/12/2022
HedgeDoc is an open-source, web-based, self-hosted, collaborative markdown editor. Images uploaded with HedgeDoc version 1.9.1 and later have an enumerable filename after the upload, resulting in potential information leakage of uploaded documents. This is especially relevant for private notes and affects all upload backends, except Lutim and imgur. This issue is patched in version 1.9.3 by replacing the filename generation with UUIDv4. If you cannot upgrade to HedgeDoc 1.9.3, it is possible to block POST requests to `/uploadimage`, which will disable future uploads.
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Analysis
by VulDB Data Team • 04/14/2022
CVE-2022-24837 represents a information disclosure vulnerability within HedgeDoc, a collaborative markdown editing platform that enables users to create and share documents in a self-hosted environment. The vulnerability stems from the predictable filename generation mechanism used for uploaded images in versions 1.9.1 and later, creating a scenario where adversaries can enumerate and access uploaded documents through systematic filename guessing. This weakness falls under CWE-200, Information Exposure, and specifically relates to CWE-384, Sensitive Information Exposure via Information Disclosure, as the predictable naming scheme reveals information about the uploaded content and potentially the document structure. The vulnerability affects all upload backends except Lutim and imgur, indicating that the issue is specifically within the core file naming implementation rather than the storage mechanisms themselves.
The technical flaw manifests in the filename generation process where HedgeDoc uses enumerable filenames instead of cryptographically secure random identifiers, allowing attackers to potentially discover and access private documents through systematic enumeration of possible filenames. This vulnerability creates a significant risk for users who store sensitive information in private notes, as the predictable naming scheme eliminates the security provided by randomization. The implementation issue aligns with ATT&CK technique T1213.002, Analysis of Datasets, where adversaries can gather information about files and their contents through systematic enumeration. The vulnerability is particularly concerning in collaborative environments where users expect privacy and confidentiality in their document sharing, as it undermines the fundamental security assumptions of the platform.
The operational impact of CVE-2022-24837 extends beyond simple information disclosure to potentially compromise user privacy and data integrity within HedgeDoc deployments. Users storing sensitive documents, confidential notes, or proprietary information face increased risk of unauthorized access through predictable filename enumeration. This vulnerability affects organizations relying on HedgeDoc for internal documentation, collaborative projects, or secure note-taking, as it creates an attack surface that allows adversaries to systematically discover and access uploaded content. The issue impacts all upload backends except Lutim and imgur, suggesting that the vulnerability is in the core upload handling mechanism rather than specific storage providers. Organizations using HedgeDoc in production environments face potential compliance violations and data exposure risks, particularly in regulated industries where document confidentiality is critical.
The vulnerability was addressed in HedgeDoc version 1.9.3 through the implementation of UUIDv4 for filename generation, which provides cryptographically secure random identifiers that eliminate the predictability of uploaded filenames. This fix directly addresses the root cause by ensuring that each uploaded file receives a unique, non-enumerable identifier that cannot be guessed or systematically discovered. Organizations unable to upgrade immediately can implement a temporary mitigation by blocking POST requests to the /uploadimage endpoint, effectively disabling future uploads while maintaining access to existing documents. This approach aligns with defensive security practices and provides a viable workaround until a full upgrade can be implemented. The mitigation strategy reflects ATT&CK technique T1566.001, Phishing, where organizations can implement network-level controls to prevent specific attack vectors, though this particular mitigation is more focused on preventing the vulnerability from being exploited rather than addressing the underlying security issue. The vulnerability highlights the importance of secure random number generation in file naming systems and demonstrates how seemingly minor implementation details can create significant security risks in collaborative platforms.