CVE-2026-32309: 
NixOS vulnerability analysis and mitigation

CVE-2026-32309 is a cleartext transmission vulnerability in Cryptomator's Hub-based unlock flow that allows an active network attacker to intercept or tamper with OAuth tokens and key-loading traffic. The vulnerability affects all Cryptomator versions prior to 1.19.1, which explicitly supported the hub+http scheme and consumed Hub endpoints from vault metadata without enforcing HTTPS. It was disclosed on March 20, 2026, and patched in version 1.19.1 released shortly after. The CVSS v3.1 base score is 7.5 (High), and the CVSS v4.0 base score is 8.7 (High) (GitHub Advisory, Feedly).

The root cause is classified as CWE-319 (Cleartext Transmission of Sensitive Information): the HubKeyLoadingStrategy class defines both hub+http and hub+https as valid schemes, and the Dagger dependency injection module binds both as legitimate key-loading strategies without enforcing transport security. AuthFlowTask consumes hubConfig.tokenEndpoint and hubConfig.authEndpoint directly via URI.create(...) without scheme validation, and HubConfig exposes all endpoint URLs as raw strings without origin consistency checks. This means a malicious or tampered vault configuration file can redirect OAuth authorization, token exchange, device registration, and encrypted key delivery traffic to attacker-controlled plaintext HTTP endpoints. Affected source files include HubKeyLoadingStrategy.java, HubKeyLoadingModule.java, AuthFlowTask.java, and HubConfig.java (GitHub Advisory).

A network-positioned attacker can passively observe OAuth bearer tokens, device registration data, and vault access tokens transmitted over plaintext HTTP, or actively tamper with endpoint responses to redirect key-delivery and authentication traffic to attacker-controlled infrastructure. Even when the vault key itself is encrypted for the device, the authentication mechanism and endpoint trust decisions remain fully exposed, potentially enabling session hijacking and unauthorized access to encrypted vault data stored on cloud infrastructure. The confidentiality impact is rated High, as sensitive authentication material can be fully exposed to interception (GitHub Advisory, Feedly).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation as of the time of disclosure (Feedly). The EPSS score is approximately 0.029% (0.000290), indicating a low probability of exploitation in the near term. No threat actor attribution has been reported, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires an active network attacker positioned on the communication path (e.g., via ARP spoofing, rogue Wi-Fi, or compromised network infrastructure) and a vault configuration that uses hub+http endpoints.

1. Reconnaissance: Identify a target using Cryptomator with Hub-based vault unlocking on a network the attacker can intercept (e.g., shared Wi-Fi, corporate LAN via ARP poisoning).
2. Position on network path: Use ARP spoofing, rogue access point, or similar man-in-the-middle technique to intercept traffic between the Cryptomator client and the Hub server.
3. Tamper with vault configuration: Modify or craft a vault configuration file so that authEndpoint, tokenEndpoint, or apiBaseUrl fields point to attacker-controlled HTTP endpoints (using the hub+http scheme).
4. Deliver malicious vault config: Distribute the tampered vault configuration to the victim (e.g., via a shared cloud storage folder, phishing, or by modifying the vault metadata on a shared drive).
5. Capture OAuth traffic: When the victim opens the vault in Cryptomator and proceeds through the Hub unlock flow, the client sends OAuth authorization requests and bearer tokens to the attacker-specified HTTP endpoints without any HTTPS enforcement or origin validation.
6. Harvest tokens: Capture bearer tokens, device registration data, and vault access tokens from the plaintext HTTP traffic using a network sniffer (e.g., Wireshark) or the attacker-controlled endpoint.
7. Access vault data: Use the captured tokens to authenticate to the legitimate Hub server and retrieve encrypted vault keys or access cloud-stored vault data (GitHub Advisory).

• Network: HTTP (plaintext, port 80) traffic from the Cryptomator client to Hub-related endpoints (OAuth token exchange, device registration, key delivery) instead of HTTPS (port 443); unexpected outbound connections to unfamiliar IP addresses or domains during vault unlock.
• File System: Vault configuration files (vault.cryptomator) containing hub+http:// in the key ID or non-HTTPS values in authEndpoint, tokenEndpoint, or apiBaseUrl fields.
• Logs: Application or proxy logs showing HTTP requests to Hub endpoints carrying Authorization: Bearer headers or OAuth code parameters in plaintext; browser history showing OAuth redirects to http:// (non-HTTPS) Hub URLs during vault unlock.
• Process Behavior: Cryptomator spawning a browser process navigating to an http:// OAuth authorization URL rather than https:// during the Hub unlock flow (GitHub Advisory).

Upgrade Cryptomator to version 1.19.1 or later, which removes support for hub+http in production builds and enforces HTTPS for all Hub endpoints including authEndpoint, tokenEndpoint, and apiBaseUrl (Cryptomator Release). Until patching is possible, users should avoid unlocking Hub-backed vaults over untrusted or unencrypted networks, and administrators should audit vault configuration files for any hub+http or non-HTTPS endpoint references. Using a VPN or network segmentation to protect authentication traffic provides additional defense in depth for environments where immediate patching is not feasible (Feedly).

The vulnerability was reported by researcher Yanchon918s and published as a GitHub Security Advisory (GHSA-vv33-h7qx-c264) by the Cryptomator maintainers on March 20, 2026 (GitHub Advisory). The release of version 1.19.1 received positive community engagement on GitHub, with 16 users reacting to the release notes. No significant broader media coverage or notable researcher commentary beyond the official advisory has been identified.