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CVE-2016-4028

Published: Dec 15, 2016Updated: May 6, 2026 Sources: CVE List NVDCWE-255
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.7%
Top 51.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

Description

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.

CVSS Vector Breakdown

AV:NAC:HPR:LUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
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Weaknesses

CWE-255

Affected Products

n/an/a
ox guardopen-xchangeCommunications
open-xchangecommercialDECommunicationsaka open-xchange gmbh, ox

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

References

http://www.securitytracker.com/id/1036154
securitytracker.com
http://www.securityfocus.com/archive/1/538732/100/0/threaded
securityfocus.com

Timeline

Published
Dec 15, 2016
Last Updated
May 6, 2026

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