LinkAce: Authorization Bypass Through User-Controlled Key
CVE-2026-45342 is a high-severity authorization bypass through user-controlled key vulnerability in LinkAce from Kovah, with a CVSS 4.0 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. Affected LinkAce versions: < 2.5.6. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.22% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of LinkAce you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
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.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- LowLimited loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- NoneNo loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA (github.com).
Official description
LinkAce is a self-hosted archive to collect website links. Prior to 2.5.6, LinkAce contains an Insecure Direct Object Reference vulnerability in the authorization policy layer that allows any authenticated user to modify resources owned by other users. The affected resource types are links, lists, tags, and notes. Both the web UI and the REST API are vulnerable. The root cause is in the update() methods of all four model policies: LinkPolicy, LinkListPolicy, TagPolicy, and NotePolicy. Each delegates to an access-check method (e.g., userCanAccessLink()) that returns true for any resource with non-private visibility, regardless of who owns it. This means any registered user can edit any public or internal resource across the entire instance. The delete() methods in the same policy files correctly require ownership via $link->user->is($user), which confirms that update was intended to be owner-only. The same flaw exists in the API layer through AuthorizesUserApiActions::userCanUpdateModel(), which mirrors the broken visibility-only check instead of the ownership check used by userCanDeleteModel(). Bulk edit operations via BulkEditController are also affected. This vulnerability is fixed in 2.5.6.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
How developers prevent this class of flaw
- For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.
- Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.
- Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
More Authorization Bypass Through User-Controlled Key vulnerabilities (CWE-639)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in LinkAce
- 7.3 High severity
- 8.1 High severity
- 8.5 High severity
- 8.1 High severity
- 8.5 High severity
- 7.3 High severity
Recent Authorization Bypass Through User-Controlled Key vulnerabilities
- 8.2 High severity
- 7.5 High severity
- 8.2 High severity
- 8.8 High severity
- 7.1 High severity
- 7.5 High severity
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