CVE-2026-27898 Vaultwarden: Unauthorized Access via Partial Update API on Another User’s Cipher

What is CVE-2026-27898?

CVE-2026-27898 is a medium-severity missing authorization vulnerability in dani-garcia vaultwarden, published on 4 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Vaultwarden is an unofficial Bitwarden compatible server written in Rust, formerly known as bitwarden_rs. Prior to version 1.35.4, an authenticated regular user can specify another user’s cipher_id and call "PUT /api/ciphers/{id}/partial" Even though the standard retrieval API correctly denies access to that cipher, the partial update endpoint returns 200 OK and exposes cipherDetails (including name, notes, data, secureNote, etc.). This issue has been patched in version 1.35.4.

Weakness: CWE-639

Which versions are affected by CVE-2026-27898?

2 open source packages ship an affected version, including vaultwarden. It affects 1 product.

Products include Dani-Garcia Vaultwarden.

How do I fix CVE-2026-27898?

Upgrade vaultwarden to 1.35.4 or later.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2026-27898 being exploited?

There is no known exploitation of CVE-2026-27898 in the wild and no public exploit code.

Other vulnerabilities in dani-garcia vaultwarden

• CVE-2024-55225 Vaultwarden vulnerable to user impersonation Critical 9.8
• CVE-2024-55224 Vaultwarden HTML injection vulnerability Critical 9.6
• CVE-2024-39924 Privilege escalation in n/a High 8.8
• CVE-2026-43912 Vaultwarden: Cross-Org Group Binding Enables Unauthorized Read And Write Access Into Another Organization High 8.7
• CVE-2026-27802 Vaultwarden: Privilege Escalation via Bulk Permission Update to Unauthorized Collections by Manager High 8.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-w9f8-m526-h7fh.