EUVD-2026-113794
GHSA-pr8g-2g62-66gf
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate as org member
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ExploitCraft POST /api/ciphers/create with restricted CollectionIds
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ExecutionNulled UserId bypasses per-collection edit check
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ImpactInject cipher synced to read-only/inaccessible collection members
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization logic validation
MITRE ATT&CK
1 technique across 1 tactic: Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | The attacker must be an authenticated, confirmed member of the target Bitwarden organization (PR:L), and the server must run an Entity Framework backend (self-hosted MySQL/PostgreSQL/SQLite) on a version before 2026.10.1. No user interaction is needed and the request is a single API call to POST /api/ciphers/create specifying the restricted CollectionIds. Limiting factors: it is not reachable by fully unauthenticated outsiders, the impact is restricted to injecting (not reading or deleting) vault items into collections, and deployments on the default MSSQL/Dapper path are not indicated as affected by the patched Entity Framework code path. |
| Impact | This is a genuine but moderate-severity authorization (not authentication) flaw, best characterized as a high-privilege-insider integrity issue rather than a widespread emergency. The vendor/CNA CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N) and the 5.3 score agree: exploitation is remote and low-complexity but requires an already-authenticated organization member (PR:L), and impact is confined to integrity (VI:L) with no confidentiality or availability loss (VC:N/VA:N) and no scope change to other systems (SC/SI/SA:N). No KEV listing and no EPSS score were supplied in the input, so there is no signal of active or probabilistically likely exploitation; the only priority signal is vuln.today's 'this_month' decision label, which is consistent with a medium, patch-when-convenient issue rather than 'act_now'/'emergency'. The practical risk is further narrowed because the description scopes the bug to Entity Framework backends (self-hosted MySQL/PostgreSQL/SQLite deployments), not the default MSSQL/Dapper path. Net: a real, confirmed insider-integrity bug worth patching on a normal cycle, not a drop-everything remote-takeover - the raw CVSS is already modest and the available signals do not elevate it. |
| Exploit ScenarioDerived | A confirmed member of a Bitwarden organization (for example a low-trust contractor granted access to only one collection) sends a crafted POST /api/ciphers/create request naming CollectionIds for collections they have read-only or no edit rights to. Because the create path nulls the cipher's UserId and treats that as administrative, the missing per-collection edit check lets the attacker inject vault items that sync to the other members of those restricted collections. A public technical write-up of the technique exists (abraxaslabs 'bitwarden-cipher-create-acl'); it is not verified as working exploit code. |
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Alert meAnalysisAIv1 – Oct 30, 2026
Bitwarden Server deployments running the Entity Framework backend on versions before 2026.10.1 let an authenticated organization member insert vault items into collections that member has no edit rights to, with the injected cipher then syncing to every member of the target collection. The bypass is reached through a single call to POST /api/ciphers/create with a nulled UserId, which the collection-assignment path treats as administrative, and no user interaction is required. Exploitation requires a confirmed organization membership on a self-hosted MySQL/PostgreSQL/SQLite deployment; the impact is confined to data integrity (writing items), not disclosure or deletion. No public exploit code has been confirmed in the available sources, the flaw is not listed in CISA KEV, and vendor patches are available.
RemediationAI
Vendor-released patch: Bitwarden Server 2026.10.1. Upgrade self-hosted Entity Framework deployments to 2026.10.1 or later, which introduces the CanEditItemsInCollections authorization check in CiphersController.PostCreate and preserves the acting user id during Entity Framework collection assignment; the official fix is tracked in https://github.com/bitwarden/server/pull/8482 and https://github.com/bitwarden/server/commit/9030c42bf7d8f9ac2ff9fee85c39588d5eb81499, and the release is published at https://github.com/bitwarden/server/releases/tag/v2026.10.1. Because the vulnerable path is specific to the Entity Framework backend, operators running MSSQL/Dapper deployments are not indicated as exposed by this code path, but consolidating on the patched release removes ambiguity across mixed environments. Until the upgrade is applied, the exposure is limited to confirmed organization members, so reducing the number of organization accounts with collection-creation workflows, and auditing recently created organization ciphers for attachед collection ids that fall outside the creator's granted collections, narrows the window; note that such auditing is detective only and does not prevent the write itself, and that deployments where members legitimately hold broad collection grants will generate large volumes of benign matches. Authentication requirements are not confirmed beyond the assessed PR:L, so treat membership revocation and account review as part of the same triage pass rather than as a standalone fix.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The root cause class is CWE-863 (incorrect authorization), realized through two related defects in the Bitwarden server codebase. First, CiphersController.PostCreate validated only that the caller belonged to the organization (OrganizationUser check) and never verified per-collection edit permission for the CollectionIds supplied in the request body. Second, in the Entity Framework repository, CreateAsyncReturnCipher nulls cipher.UserId for organization-owned ciphers because the row itself stores no user id; that nulled value was then passed into the collection-assignment query, where a null acting user is treated as administrative and therefore short-circuits the normal per-user collection scoping. The combination allows a regular (non-admin) organization member to attach a new cipher to collections they cannot edit, or to collections they cannot see at all. The patch adds a CanEditItemsInCollections check in CiphersController.PostCreate that throws NotFoundException when the caller lacks edit rights, and captures the acting user id (savingUserId) before the nulling step so collection assignment remains scoped to the caller. Tests added with the fix confirm that owners with AllowAdminAccessToAllCollectionItems short-circuit the new check, while ordinary members without grants receive a 404. Because the defective code lives in the Infrastructure.EntityFramework repository, the affected surface is the Entity Framework backend (self-hosted MySQL, PostgreSQL, SQLite) rather than the MSSQL/Dapper path referenced in the CPE cpe:2.3:a:bitwarden:server:*:*:*:*:*:*:*:*.
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Requires an authenticated org member (PR:L) over the network with no interaction; impact is integrity-only (inject items into collections), with no confidentiality or availability loss.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
DescriptionCVE.org
Bitwarden Server before 2026.10.1 on Entity Framework backends contains an authorization bypass vulnerability that allows organization members to add ciphers to collections they cannot edit. Attackers can call POST /api/ciphers/create, where a nulled UserId is treated as administrative, to inject vault items synced to read-only or inaccessible collections' members.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
Account takeover in self-hosted Bitwarden Server before 2026.6.0 lets a low-privileged organization member steal any oth
Provider service users in Bitwarden Server Cloud can hijack arbitrary organizations via unauthorized API endpoint access
Authentication bypass in Bitwarden Server versions prior to 2026.4.1 allows authenticated users with SCIM management pri
Authentication bypass in self-hosted Bitwarden Server versions 2025.6.0 through 2026.5.0 backed by Microsoft SQL Server
Bitwarden through 2023.2.1 offers password auto-fill when the second-level domain matches, e.g., a password stored for a
Privilege escalation in self-hosted Bitwarden Server before 2026.5.0 lets an authenticated organization member holding a
Bitwarden Windows desktop application versions prior to v2023.4.0 store biometric keys in Windows Credential Manager, ac
Audit log integrity across all Bitwarden Server organizations can be undermined by any authenticated user, who may injec
Broken access control in Bitwarden Server before 2026.5.0 exposes organization billing data to any authenticated user vi
Bitwarden Server prior to v2026.4.1 allows any authenticated user to write ciphers (encrypted credentials) into arbitrar
Malicious code injection in Bitwarden CLI 2026.4.0 distributed via npm for 90 minutes on April 22, 2026, enables remote
Bitwarden Server 1.35.1 allows SSRF because it does not consider certain IPv6 addresses (ones beginning with fc, fd, fe,
Exploit-DB