CouchCMS: Authorization Bypass Through User-Controlled Key
CVE-2026-29002 is a high-severity authorization bypass through user-controlled key vulnerability in CouchCMS, with a CVSS 3.1 base score of 7.2 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. Affected CouchCMS versions: 2.4.0 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.44% 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 CouchCMS you run against the affected versions below, and install the vendor's latest release.
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.
- Privileges required
- HighAdministrator-level access is required first.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.6 | High | CNA (vulncheck.com) |
| CVSS 3.1 | 7.2 | High | CNA (vulncheck.com) |
Official description
CouchCMS contains a privilege escalation vulnerability that allows authenticated Admin-level users to create SuperAdmin accounts by tampering with the f_k_levels_list parameter in user creation requests. Attackers can modify the parameter value from 4 to 10 in the HTTP request body to bypass authorization validation and gain full application control, circumventing restrictions on SuperAdmin account creation and privilege assignment.
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: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
Technical write-ups (may include proof of concept)
- gist.github.com/thepiyushkumarshukla/477e2d2bbbe8cc3ec0d640c50f0cf9e1Exploit, Third Party Advisory
Other references
- couchcms.com/Product
Recent Authorization Bypass Through User-Controlled Key vulnerabilities
- 7.1 High severity
- 7.1 High severity
- 8.1 High severity
- 7.7 High severity
- 8.1 High severity
- 7.6 High severity
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