CVE-2026-40196
Sysadminsmedia Homebox ≤ 0.25.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:NSummary
CVE-2026-40196 is a high-severity Incorrect Ownership Assignment (CWE-708) vulnerability in Sysadminsmedia Homebox. Its CVSS base score is 8.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 16th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-16 (Security and Privacy Attributes) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-40196 is an access control bypass vulnerability (CWE-708) in HomeBox, an open-source home inventory and organization system. Versions prior to 0.25.0 fail to properly revoke a user's defaultGroup ID after their invitation to a group is rescinded. Although the web interface correctly blocks access to the group's contents post-revocation, the API does not validate the persisted defaultGroup ID when the X-Tenant header is absent from requests, enabling unauthorized operations on group resources. The vulnerability carries a CVSS v3.1 base score of 8.1 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N).
A low-privileged authenticated user (PR:L) who was previously invited to a group can exploit this issue remotely over the network (AV:N) with low attack complexity (AC:L) and no user interaction (UI:N). By omitting the X-Tenant header in API calls, the attacker leverages their unchanged defaultGroup ID to perform full CRUD (create, read, update, delete) operations on the group's collections, bypassing revocation controls. This results in high impacts to confidentiality and integrity, allowing data exfiltration, modification, or injection without affecting availability.
The vulnerability is fixed in HomeBox version 0.25.0. Security practitioners should upgrade to this version immediately. Additional details are available in the release notes at https://github.com/sysadminsmedia/homebox/releases/tag/v0.25.0 and the GitHub security advisory at https://github.com/sysadminsmedia/homebox/security/advisories/GHSA-6pvm-v73p-p6m9.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23539
Vulnerability Data
HomeBox is a home inventory and organization system. Versions prior to 0.25.0 contain a vulnerability where the defaultGroup ID remained permanently assigned to a user after being invited to a group, even after their access to that group was revoked.…
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While the web interface correctly enforced the access revocation and prevented the user from viewing or modifying the group's contents, the API did not. Because the original group ID persisted as the user's defaultGroup, and this value was not properly validated when the X-Tenant header was omitted, the user could still perform full CRUD operations on the group's collections through the API, bypassing the intended access controls. This issue has been fixed in version 0.25.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 4 hardening rules · 3 OS baselines
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Mitigating Controls (NIST 800-53 r5) AI
Enforces approved authorizations on resource access, which structurally prevents assignment of ownership outside the intended control sphere.
Provides the mechanism to associate and manage security attributes such as ownership, directly stopping incorrect owner assignment.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Defining, enforcing and reviewing access permissions and entitlements directly addresses correct ownership assignment for resources.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Access-control policy can mandate correct ownership assignment, but does not prescribe how ownership is technically enforced.
Identity-management processes define who may own resources, yet do not guarantee correct assignment at creation time.
Access-rights provisioning includes ownership assignment; fixing CWE-708 directly supports this control's intent.
Role definitions can require ownership accountability, but the control itself does not address technical assignment errors.
Privileged-access rules often include ownership checks, yet the control focuses on elevated rights rather than ownership correctness.
Information-access-restriction mechanisms rely on correct ownership; eliminating incorrect ownership strengthens this control.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
RHEL 7 (1 rule)
- V-204392 The Red Hat Enterprise Linux operating system must be configured so that the file permissions, ownership, and group membership of system files and commands match the vendor values. prevents CWE-708