CyberSecBulletin
CVE-2026-57520NVD status: Analyzed

server: Missing Authorization

Published Updated By the CyberSecBulletin desk

CVE-2026-57520 is a high-severity missing authorization vulnerability in server from Bitwarden, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 2026.5.0 as the first without the flaw, so updating server to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.64% chance of exploitation within 30 days, higher than 51% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update server to 2026.5.0 or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
Bitwardenserverbefore 2026.5.02026.5.0

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
HighData or code can be modified at will.
Availability
LowPerformance or availability is reduced.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L. Scored by CNA (vulncheck.com).

Scoring systemScoreSeverityScored by
CVSS 4.07.1HighCNA (vulncheck.com)
CVSS 3.17.1HighCNA (vulncheck.com)

Official description

Bitwarden Server before 2026.5.0 contains a privilege escalation vulnerability that allows authenticated Custom users with ManageUsers permission to remove Admin accounts from an organization by exploiting a missing role hierarchy check in the bulk user-remove endpoint. Attackers can supply Admin organization-user IDs in a bulk DELETE request to bypass the guard enforced on the single-user removal path, effectively removing one or more Admin accounts from an organization.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

How developers prevent this class of flaw

  • Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
  • Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework and the OWASP ESAPI Access Control feature.

More Missing Authorization vulnerabilities (CWE-862)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in server

All server vulnerabilities

Recent Missing Authorization vulnerabilities

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