CVE-2026-32317: 
NixOS vulnerability analysis and mitigation

CVE-2026-32317 is an integrity check vulnerability in Cryptomator for Android that enables a man-in-the-middle (MITM) attack on the Hub key loading mechanism. Prior to version 1.12.3, the Android client trusted API and authentication endpoints specified in the vault.cryptomator configuration file without performing host authenticity checks, allowing an attacker who can tamper with that file to redirect token requests to a malicious endpoint. The vulnerability affects all Cryptomator for Android versions before 1.12.3 and was disclosed on March 20, 2026. It carries a CVSS v3.1 score of 7.6 (High) per the GitHub Security Advisory, or 5.9 (Medium) per NVD scoring (GitHub Advisory, Feedly).

The root cause is a combination of CWE-346 (Origin Validation Error), CWE-354 (Improper Validation of Integrity Check Value), CWE-451 (UI Misrepresentation of Critical Information), and CWE-923 (Improper Restriction of Communication Channel to Intended Endpoints). When a user unlocks a Hub-backed vault, the Android client reads endpoint URLs directly from the vault.cryptomator configuration file and contacts them without verifying host authenticity. An attacker who can modify this file — for example, via a compromised or attacker-controlled cloud storage path — can substitute a malicious API endpoint while keeping a legitimate authentication endpoint, causing the client to send authentication tokens to the attacker-controlled server. The precondition for exploitation is the ability to alter the vault.cryptomator file in the victim's storage or sync path (GitHub Advisory).

Successful exploitation allows an attacker to exfiltrate authentication tokens used during Hub vault unlock, potentially enabling unauthorized access to the victim's Cryptomator Hub account. Confidentiality impact is high (token theft), while integrity impact is low and availability is unaffected. Importantly, because Cryptomator Hub uses end-to-end encryption, the encrypted vault data itself was never directly at risk — only the Hub authentication tokens are exposed (GitHub Advisory).

No public proof-of-concept exploit code has been published, and the Cryptomator team has stated they are not aware of any active exploitation of this vulnerability (GitHub Advisory). The EPSS score is approximately 0.011% (0.000110), indicating a very low probability of exploitation in the near term (Feedly). The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires the attacker to have write access to the victim's vault configuration file, which significantly limits the attack surface.

1. Gain write access to vault configuration: The attacker obtains the ability to modify the victim's vault.cryptomator file — for example, by compromising a shared cloud storage account, exploiting misconfigured file permissions, or performing a supply-chain attack on the sync path.
2. Tamper with the vault config: The attacker edits the vault.cryptomator file to replace or supplement the Hub API endpoint URL with a URL pointing to an attacker-controlled server, while leaving the legitimate authentication endpoint intact to avoid raising suspicion.
3. Wait for victim to unlock the vault: The victim opens the Cryptomator Android app and attempts to unlock their Hub-backed vault, triggering the Hub key loading mechanism.
4. Intercept authentication token: The client, without verifying host authenticity, contacts the malicious API endpoint specified in the tampered config. The attacker's server receives and logs the authentication token sent by the client.
5. Use exfiltrated token: The attacker uses the captured token to authenticate to the legitimate Cryptomator Hub, potentially gaining access to vault keys or account resources (GitHub Advisory).

• File System: Unexpected or unauthorized modifications to the vault.cryptomator configuration file (check file modification timestamps and hash values against known-good baselines).
• Network: Outbound HTTPS connections from the Cryptomator Android app to unexpected or unrecognized Hub API endpoints not matching the organization's legitimate Cryptomator Hub server hostname.
• Logs: Authentication token requests observed in server logs originating from IP addresses or user agents inconsistent with the legitimate user's device or location.
• Behavioral: Vault unlock failures or unexpected authentication prompts that may indicate the client is contacting an unresponsive or misconfigured malicious endpoint (GitHub Advisory).

Cryptomator has released version 1.12.3 for Android, which introduces Trust-on-First-Contact (TOFU) host verification during vault unlock, requiring explicit user approval for new or changed Hub endpoints (GitHub Release). Users should update to version 1.12.3 or later immediately. If upgrading is not immediately possible, two workarounds are recommended: (1) restrict outbound client network access so Cryptomator can only reach trusted Hub hosts, and (2) protect vault configuration integrity through strict file permissions and use of trusted sync/storage paths (GitHub Advisory).

Cryptomator published a vendor blog post on March 13, 2026, disclosing the Hub vault unlock vulnerability ahead of the formal CVE publication (Cryptomator Blog). The advisory emphasized that vault data was never at risk due to end-to-end encryption, and that no active exploitation was known, which likely contributed to a measured community response. Social media coverage was limited, with a mention noted on Mastodon (Mastodon).