CVE-2016-4028

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Summary

CVECVE-2016-4028
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2016-12-15 06:59:07 UTC
Updated2026-05-06 22:30:45 UTC
DescriptionAn 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.

Risk And Classification

Primary CVSS: v3.0 7.5 HIGH from [email protected]

CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001480000 probability, percentile 0.348020000 (date 2026-05-11)

Problem Types: CWE-255 | n/a

VersionSourceTypeScoreSeverityVector
3.0[email protected]Primary7.5HIGHCVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
2.0[email protected]Primary3.5AV:N/AC:M/Au:S/C:P/I:N/A:N

CVSS v3.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 Breakdown

Access Vector
Network
Access Complexity
Medium
Authentication
Single
Confidentiality
Partial
Integrity
None
Availability
None

AV:N/AC:M/Au:S/C:P/I:N/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Open-xchange Ox Guard All rev7 All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na N/a affected n/a Not specified

References

ReferenceSourceLinkTags
Open-Xchange Guard Error Code Response Lets Remote Authenticated Users Obtain Authentication Information - SecurityTracker af854a3a-2127-422b-91ae-364da2661108 www.securitytracker.com Third Party Advisory, VDB Entry
SecurityFocus af854a3a-2127-422b-91ae-364da2661108 www.securityfocus.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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