Psono Server CE && EE versions 4.0.33 through 7.2.3 compared the request path for the bulk-secret-read endpoint with a hard-coded unprefixed path. In deployments configured with URLPREFIX, the comparison failed and the POST request was authorized using write scope instead of read scope. An authenticated remote attacker with an unusual read-disabled, write-enabled API key could therefore retrieve encrypted secret data and nonces through the prefixed bulk-secret-read endpoint despite lacking read permission. The default configuration without URLPREFIX was not affected.

Psono Server CE && EE versions 0.1.0 through 7.2.3 accepted a user-controlled host when configuring a personal Duo device and passed it to the Duo client without an allowlist or explicit timeout. An authenticated remote attacker could cause the server to connect to selected hosts over HTTPS on port 443 and distinguish failure modes, providing an internal DNS and service-reachability oracle. Connections still required TLS certificate validation, and the flaw did not provide arbitrary protocol or port access. Unresponsive targets could also occupy a server worker until the operating-system timeout.

Psono Server CE & EE versions 3.1.0 through 7.2.3 did not consume a stored WebAuthn challenge after assertion verification. An unauthenticated remote attacker who possessed the user's password and one captured valid WebAuthn assertion could replay that assertion with separate login tokens while the stored challenge remained unchanged, bypassing the WebAuthn second factor. The attack required capture of a valid assertion and did not itself disclose plaintext secrets.

Psono Server (CE & EE) versions 1.0.0 through 7.2.3 did not enforce the direction of file-transfer credentials on file-repository operations. An authenticated remote attacker with read-only access to a file could present a download transfer to the upload endpoint, obtain a signed upload URL for an attacker-selected object key, and append a chunk to the owner's file. Exploitation could upload or overwrite repository objects and consume storage, subject to transfer size, chunk-count, and lifetime limits.

Psono Server versions 5.3.5 through 7.2.3 used a permission class that did not enforce token write scope when claiming a device code. An authenticated remote attacker holding a restricted API key-derived session could claim an attacker-controlled device code and obtain a full read-write session valid for up to 365 days, bypassing the original token's scope and lifetime restrictions. This did not bypass two-factor authentication or directly disclose plaintext secrets.

A Cross-Site Scripting (XSS) vulnerability has been identified in Psono-Client’s handling of vault entries of type websitepassword and bookmark, as used in Bitdefender SecurePass. The client does not properly sanitize the URL field in these entries. As a result, an attacker can craft a malicious vault entry (or trick a user into creating or importing one) with a javascript:URL. When the user interacts with this entry (for example, by clicking or opening it), the application will execute the malicious JavaScript in the context of the Psono vault. This allows an attacker to run arbitrary code in the victim’s browser, potentially giving them access to the user’s password vault and sensitive data.