An issue was discovered in Open-Xchange OX Guard before 2.4.0-rev8.
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.0 · NVD. Fix status from CNA.
Summary
An issue was discovered in Open-Xchange OX Guard before 2.4.0-rev8. OX Guard uses an authentication token to identify and transfer guest users' credentials. The OX Guard API acts as a padding oracle by responding with different error codes depending on whether the provided token matches the encryption padding. In combination with AES-CBC, this allows attackers to guess the correct padding. Attackers may run brute-forcing attacks on the content of the guest authentication token and discover user credentials. For a practical attack vector, the guest users needs to have logged in, the content of the guest user's "OxReaderID" cookie and the value of the "auth" parameter needs to be known to the attacker.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:open-xchange:ox_guard:*:rev7:*:*:*:*:*:* | up to 2.4.0 | Vulnerable | Open-Xchange GmbH |
- cpe:2.3:a:open-xchange:ox_guard:*:rev7:*:*:*:*:*:* Versions up to 2.4.0 Vulnerable ·Open-Xchange GmbH
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2016-4028
- 2026-10-03 Alias added: GHSA-qxh8-75pv-8vmg
References
—
More Open-Xchange GmbH Ox Guard vulnerabilities
- TI-2015-07026 An issue was discovered in Open-Xchange Guard before 2.2.0-rev8. CVSS 3.0HIGH 8.8
- TI-2018-07786 OX Guard 2.8.0 has CSRF. CVSS 3.0HIGH 8.8
- TI-2020-17472 OX Guard 2.10.4 and earlier allows a Denial of Service via a WKS server that responds… CVSS 3.1HIGH 7.5
- TI-2016-05890 An issue was discovered in Open-Xchange OX Guard before 2.4.2-rev5. CVSS 3.0MEDIUM 6.1
- TI-2016-05889 An issue was discovered in Open-Xchange OX Guard before 2.4.2-rev5. CVSS 3.0MEDIUM 6.1
- TI-2016-05887 An issue was discovered in Open-Xchange OX Guard before 2.4.2-rev5. CVSS 3.0MEDIUM 6.1
Sources
- CVE-2016-4028 · CVE Program
- CVE-2016-4028 · NVD
- FIRST EPSS
- GHSA-qxh8-75pv-8vmg · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences