CVE-2026-27898
Description
A flaw was found in Vaultwarden, an unofficial Bitwarden compatible server. An authenticated regular user can exploit this by specifying another user’s cipher identifier (cipher_id) and making a partial update request to the API. This action bypasses standard access controls, leading to the exposure of sensitive cipher details, such as names, notes, and data, belonging to other users. This vulnerability results in information disclosure.
Statement
This MODERATE information disclosure vulnerability in Vaultwarden allows an authenticated user to retrieve another user's cipher details via the partial update API endpoint (CWE-639 IDOR). Exploitation requires network access and valid authentication (PR:L). Impact is limited to high confidentiality loss (exposure of names, notes, secure notes); no integrity or availability impact. Affects versions prior to 1.35.4. Red Hat does not ship Vaultwarden.
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Access control checks for specific user data or functionality can be bypassed.
Access Control
Technical Impact: Gain Privileges or Assume Identity
Horizontal escalation of privilege is possible (one user can view/modify information of another user).
Access Control
Technical Impact: Gain Privileges or Assume Identity
Vertical escalation of privilege is possible if the user-controlled key is actually a flag that indicates administrator status, allowing the attacker to gain administrative access.
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