CVE Tools
Sign in

CVE-2016-4028

Published: Dec 15, 2016Updated: May 6, 2026 Sources: CVE List NVDCWE-255
7.5HIGH
NVD MITRE
EPSS Score
0.6%
Top 54.5%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
Self-Check
Not 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.

No summary for this CVE yet.

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
Open in CVSS calculator →

Weaknesses

CWE-255

Affected Products

open-xchange
commercial·DEaka open-xchange gmbh, ox
ox guard
Communications
and 1 more affected products View all →

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.
Is your org exposed to CVE-2016-4028?We can run the check for you — a free external exposure review, no install. Check my exposure

References

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

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2016-4028 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows