CVE-2026-32318 in cryptomator
Summary
by MITRE • 03/20/2026
Cryptomator for IOS offers multi-platform transparent client-side encryption for files in the cloud. Prior to version 2.8.3, an integrity check vulnerability allows an attacker tamper with the vault configuration file leading to a man-in-the-middle vulnerability in Hub key loading mechanism. Before this fix, the client trusted endpoints from the vault config without host authenticity checks, which could allow token exfiltration by mixing a legitimate auth endpoint with a malicious API endpoint. Impacted are users unlocking Hub-backed vaults with affected client versions in environments where an attacker can alter the vault.cryptomator file. This issue has been patched in version 2.8.3.
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Analysis
by VulDB Data Team • 03/27/2026
The vulnerability identified as CVE-2026-32318 affects Cryptomator for iOS clients prior to version 2.8.3, specifically targeting the integrity validation mechanisms of vault configuration files. This flaw represents a critical security weakness in the client-side encryption framework that undermines the trust model between the client application and remote endpoints. The vulnerability stems from insufficient validation of the vault configuration file, which contains critical endpoint information necessary for establishing secure connections to cloud storage services. The affected implementation fails to perform proper host authenticity checks when processing the vault configuration, creating an attack surface that allows malicious actors to manipulate the configuration file without detection.
The technical flaw manifests in the Hub key loading mechanism where the client application blindly trusts endpoint information retrieved from the vault configuration file without performing cryptographic validation or host verification. This represents a classic violation of the principle of least privilege and trust verification, as outlined in CWE-284 Access Control. The vulnerability creates a man-in-the-middle attack vector where an attacker can modify the vault.cryptomator file to substitute legitimate authentication endpoints with malicious counterparts. When users attempt to unlock Hub-backed vaults using affected client versions, the application processes the compromised configuration and establishes connections to attacker-controlled endpoints, enabling unauthorized access to authentication tokens and sensitive session data.
The operational impact of this vulnerability extends beyond simple data theft to encompass complete compromise of the client-side encryption security model. Users operating with vulnerable versions face significant risk of credential exposure, as the authentication tokens used to access cloud storage services can be intercepted and exfiltrated by attackers who manipulate the vault configuration. This vulnerability particularly affects enterprise environments where network traffic may be subject to manipulation by insider threats or compromised network infrastructure. The attack scenario requires minimal sophistication from the attacker, as they only need to modify the vault configuration file to inject malicious endpoints, making this vulnerability exploitable in various threat scenarios including network-based attacks and supply chain compromises.
Security mitigations for this vulnerability involve immediate upgrade to Cryptomator version 2.8.3 or later, which implements proper endpoint validation and host authenticity checks. Organizations should also consider implementing network monitoring to detect suspicious endpoint modifications and conduct regular security audits of vault configuration files. The fix addresses the underlying issue by introducing cryptographic validation of endpoint information and implementing proper certificate pinning mechanisms. This aligns with ATT&CK technique T1566.002 for credential access through man-in-the-middle attacks and demonstrates the importance of implementing proper input validation and endpoint verification as outlined in the OWASP Top 10 security principles. Users should also verify the integrity of their vault configuration files through checksum validation and maintain secure backup copies of legitimate configuration data to prevent successful exploitation of this vulnerability.