CVE-2026-73230 in Ente
Summary
by MITRE • 08/11/2026
Ente provides end-to-end encrypted cloud services and security tools. Prior to 2026.07.28, Ente 2of3 card format version 1 stored the secret byte length and 32-bit FNV-1a checksum in cleartext on every card, allowing someone with one card to test candidate secrets offline and recover low-entropy or predictable secrets. This issue is fixed in version 2026.07.28.
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Analysis
by VulDB Data Team • 08/11/2026
The vulnerability in Ente's 2of3 card format version 1 represents a significant cryptographic weakness that undermines the security of their end-to-end encrypted cloud services. This flaw exposes critical information in cleartext format on every card, specifically storing both the secret byte length and a 32-bit FNV-1a checksum alongside the encrypted data. The presence of these cleartext elements creates an attack surface that allows adversaries to perform offline brute force attacks against the secret values, particularly targeting low entropy or predictable secrets that could be recovered through systematic testing.
The technical implementation of this vulnerability stems from improper cryptographic design principles where metadata necessary for decryption is stored in plaintext rather than being protected alongside the encrypted content. This approach violates fundamental security practices outlined in standards such as CWE-310 and CWE-312, which specifically address weaknesses related to cleartext storage of sensitive data and insufficient entropy in cryptographic keys. The FNV-1a checksum, while intended for integrity verification, becomes a vulnerability when stored in cleartext because it provides attackers with immediate feedback on the correctness of their guesses during offline testing phases.
The operational impact of this vulnerability is substantial for Ente's security model, as it transforms what should be a computationally expensive offline attack into a potentially successful brute force operation. Attackers with access to just one card can now systematically test candidate secrets against the stored checksum and byte length information, dramatically reducing the time and computational resources required to compromise the system. This weakness particularly affects users who employ predictable or low-entropy secrets, making the entire ecosystem vulnerable to targeted attacks that exploit human tendencies toward memorable but weak passwords.
This vulnerability aligns with several ATT&CK framework techniques including T1213.002 (Backup Data Access) and T1566 (Phishing), as it creates opportunities for adversaries to gain unauthorized access to encrypted data through the exploitation of cleartext metadata. The fix implemented in version 2026.07.28 likely involves reworking the card format to either eliminate the cleartext storage of metadata or protect it using appropriate cryptographic mechanisms. Organizations should implement immediate mitigation strategies including mandatory secret entropy requirements, regular security audits, and comprehensive user education about the importance of strong secrets. The remediation process should also include re-encryption of existing cards and implementation of proper key derivation functions that prevent the leakage of information through checksums and metadata storage patterns.