CVE-2016-1566

Cross-site scripting (XSS) vulnerability in the file browser in Guacamole 0.9.8 and 0.9.9, when file transfer is enabled to a location shared by multiple users, allows remote authenticated users to inject arbitrary web script or HTML via a crafted filename. NOTE: this vulnerability was fixed in guacamole.war on 2016-01-13, but the version number was not changed.

Published: 2017-02-02 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2016-1566 is rated Moderate Risk (51.7/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.22%). Core evidence: EPSS rose +2.03% over the last day, indicating growing attacker interest. Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2016-1566

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.18% 2.22% +2.03%
2 2025-03-30 0.36% 0.18% -0.18%
3 2025-03-29 0.36%

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-1566

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.4 3.0 MEDIUM
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
2.3 2.7 [email protected]
3.5 2.0 LOW
AV:N/AC:M/Au:S/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
6.8 2.9 [email protected]

Weakness enumeration for CVE-2016-1566

OS Trackers for CVE-2016-1566

vendor priority summary link
ubuntu medium CVE-2016-1566 medium priority: Ubuntu including 2 source packages (guacamole-client, guacamole-server), 18 status rows across 9 suites (artful, bionic, cosmic, precise, trusty, upstream, xenial, yakkety, zesty): ignored 6, not-affected 6, DNE 4, needed 2. https://ubuntu.com/security/CVE-2016-1566

Affected software / configurations for CVE-2016-1566

Vendor Product Version Raw CPE
apache guacamole 0.9.8 cpe:2.3:a:apache:guacamole:0.9.8:*:*:*:*:*:*:*
apache guacamole 0.9.9 cpe:2.3:a:apache:guacamole:0.9.9:*:*:*:*:*:*:*

References for CVE-2016-1566

cvelogic Threat Intelligence