CVE-2020-8196
Citrix ADC, Gateway, and SD-WAN WANOP Appliance Information Disclosure Vulnerability
Description
CVE-2020-8196 is a MEDIUM information disclosure vulnerability affecting Citrix Application Delivery Controller (ADC), Gateway, and SD-WAN WANOP appliances, carrying a CVSS 3.1 score of 4.3. Improper access control in these products allows authenticated low-privileged users to obtain limited sensitive information that should be restricted to administrators. Affected products include Citrix ADC firmware (versions 10.5 through 13.0), NetScaler Gateway firmware (versions 10.5 through 12.1), Gateway firmware (13.0), and SD-WAN WANOP (versions 10.2 through 11.1). This CVE is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog with a remediation deadline of 2022-05-03. With an EPSS score of 0.66204 (98.50th percentile), this vulnerability shows substantial real-world exploitation activity and warrants prompt remediation.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:NOpen in CalculatorCWEs
Affected Products
| Vendor | Product | Version |
|---|---|---|
| citrix | application delivery controller firmware | >= 10.5, < 10.5-70.18; >= 11.1, < 11.1-64.14; >= 12.0, < 12.0-63.21; >= 12.1, < 12.1-57.18; >= 13.0, < 13.0-58.30 |
| citrix | netscaler gateway firmware | >= 10.5, < 10.5-70.18; >= 11.1, < 11.1-64.14; >= 12.0, < 12.0-63.21; >= 12.1, < 12.1-57.18 |
| citrix | gateway firmware | >= 13.0, < 13.0-58.30 |
| citrix | sd-wan wanop | >= 10.2, < 10.2.7; >= 11.0, < 11.0.3d; >= 11.1, < 11.1.1a |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
References
- http://packetstormsecurity.com/files/160047/Citrix-ADC-NetScaler-Local-File-Inclusion.html(Third Party Advisory, VDB Entry)
- https://support.citrix.com/article/CTX276688(Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-8196(US Government Resource)
Weakness Type
CWE-284: Improper Access Control
CVE-2020-8196 is classified under CWE-284 — Improper Access Control. This weakness occurs when a product does not properly restrict access to resources, allowing unauthorized actors to read, modify, or interact with system components beyond their intended privilege level. Access control encompasses authentication (verifying identity), authorization (verifying permissions), and accountability mechanisms. When these mechanisms fail, users may access data or functionality that should be restricted to higher-privileged roles.
In the context of Citrix ADC and Gateway appliances, this improper access control allows low-privileged authenticated users to retrieve configuration details and sensitive information normally restricted to administrative accounts. Given that these appliances serve as critical network infrastructure components handling SSL/TLS termination, load balancing, and VPN access, any unauthorized information disclosure can provide attackers with valuable reconnaissance data for further exploitation.
Learn more: CWE-284 — Improper Access Control
Impact Analysis
CVE-2020-8196 carries a CVSS 3.1 score of 4.3 (MEDIUM) with Unchanged Scope.
Confidentiality (LOW): Successful exploitation allows a low-privileged authenticated user to access limited sensitive information from the Citrix ADC, Gateway, or SD-WAN WANOP appliance. While the data exposure is restricted in scope, it can include configuration details and system parameters valuable for reconnaissance.
Integrity (NONE): No integrity impact has been identified. The vulnerability does not allow modification of data or system configurations.
Availability (NONE): No availability impact has been identified. The vulnerability does not enable denial of service or disruption of appliance operations.
Scope Unchanged: The vulnerability's scope is Unchanged, meaning the impact is confined to the vulnerable Citrix appliance itself and does not extend to other components in the network infrastructure.
With an EPSS score of 0.66204 (98.50th percentile), this vulnerability ranks in the top tier of exploited vulnerabilities despite its medium severity, highlighting that attackers frequently target information disclosure flaws as stepping stones to more severe attacks.
Exploit Maturity
CVE-2020-8196 has confirmed active exploitation in the wild and is listed in CISA's Known Exploited Vulnerabilities catalog.
Exploit status: This vulnerability has been actively exploited as confirmed by its KEV listing. The EPSS score of 0.66204 (98.50th percentile) places it among the most likely vulnerabilities to be exploited. Public exploit references are available, including a local file inclusion technique documented on Packet Storm Security.
Ransomware association: No direct ransomware association has been confirmed for CVE-2020-8196 per current KEV data. However, the vulnerability is frequently exploited alongside more critical Citrix vulnerabilities (such as CVE-2019-19781) as part of multi-stage attack chains.
Attack surface: The vulnerability requires network access and low-level authentication. Exploit code and techniques are publicly documented, lowering the barrier to exploitation. Organizations exposing Citrix ADC or Gateway management interfaces to the internet are at highest risk.
KEV deadline: CISA required federal agencies to remediate this vulnerability by 2022-05-03. All organizations should treat this deadline as a strong recommendation for their own remediation timelines.
Remediation
- Apply vendor patches immediately. Update Citrix ADC to version 13.0-58.30 or later, 12.1-57.18 or later, 12.0-63.21 or later, 11.1-64.14 or later, or 10.5-70.18 or later. Update Citrix SD-WAN WANOP to version 11.1.1a, 11.0.3d, or 10.2.7 or later. Consult the Citrix advisory CTX276688 for detailed patch guidance.
- Inventory all affected Citrix appliances. Identify every Citrix ADC, Gateway, and SD-WAN WANOP instance in your environment. Verify firmware versions against the affected ranges (ADC 10.5-13.0, Gateway 10.5-13.0, SD-WAN WANOP 10.2-11.1).
- Restrict management interface access. Ensure that Citrix appliance management interfaces are not exposed to the public internet. Implement network segmentation and access control lists to limit management access to trusted administrator networks only.
- Review user privileges and access logs. Audit user accounts on affected appliances for unauthorized access or privilege escalation. Examine logs for indicators of exploitation, particularly requests from low-privileged accounts accessing restricted administrative endpoints.
- Implement defense-in-depth monitoring. Deploy intrusion detection signatures targeting Citrix ADC exploitation patterns. Enable verbose logging on affected appliances and forward logs to a centralized SIEM for correlation analysis.
- Conduct a post-remediation verification. After applying patches, verify the fix by confirming that low-privileged users can no longer access restricted information. Document all remediation actions and update vulnerability management records.
Technical Details
CVE-2020-8196 is a MEDIUM-severity vulnerability in Citrix ADC, Gateway, and SD-WAN WANOP appliances exploitable over the network. The attack complexity is low, requiring no specialized conditions beyond basic network connectivity. Low-level authentication is required, meaning the attacker must possess valid credentials for a non-administrative account. No user interaction is needed for exploitation.
Technical mechanism: The vulnerability stems from improper access control in the management interface of affected Citrix appliances. Authenticated users with limited privileges can send specially crafted requests to administrative endpoints that fail to properly enforce role-based access restrictions. The appliance processes these requests and returns configuration data or system parameters that should only be accessible to administrators.
Affected products and versions: Citrix ADC firmware (>= 10.5 < 10.5-70.18, >= 11.1 < 11.1-64.14, >= 12.0 < 12.0-63.21, >= 12.1 < 12.1-57.18, >= 13.0 < 13.0-58.30), NetScaler Gateway firmware (>= 10.5 < 10.5-70.18, >= 11.1 < 11.1-64.14, >= 12.0 < 12.0-63.21, >= 12.1 < 12.1-57.18), Gateway firmware (>= 13.0 < 13.0-58.30), and SD-WAN WANOP (>= 10.2 < 10.2.7, >= 11.0 < 11.0.3d, >= 11.1 < 11.1.1a).
CVSS 3.1 vector analysis: The vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N reflects a network-based attack with low complexity requiring low privileges, no user interaction, unchanged scope, and low confidentiality impact with no integrity or availability impact.
Frequently Asked Questions
Is CVE-2020-8196 being actively exploited?
Yes, CVE-2020-8196 is actively exploited in the wild. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog with a remediation deadline of 2022-05-03. The EPSS score of 0.66204 (98.50th percentile) confirms a very high exploitation likelihood. Public exploit techniques, including local file inclusion methods, have been documented.
What products are affected by CVE-2020-8196?
CVE-2020-8196 affects Citrix Application Delivery Controller (ADC) firmware versions 10.5 through 13.0, NetScaler Gateway firmware versions 10.5 through 12.1, Gateway firmware version 13.0, and Citrix SD-WAN WANOP versions 10.2 through 11.1. Specific fixed versions are available for each product line. Consult the Citrix advisory CTX276688 for the complete list.
How do I fix CVE-2020-8196?
Update affected Citrix appliances to the patched firmware versions specified in Citrix advisory CTX276688. For ADC, update to 13.0-58.30, 12.1-57.18, 12.0-63.21, 11.1-64.14, or 10.5-70.18 depending on your version branch. For SD-WAN WANOP, update to 11.1.1a, 11.0.3d, or 10.2.7. Restrict management interface access to trusted networks and review access logs for signs of exploitation.
How severe is CVE-2020-8196?
CVE-2020-8196 is rated MEDIUM with a CVSS 3.1 score of 4.3. While the direct impact is limited to information disclosure, its high EPSS score of 0.66204 (98.50th percentile) and KEV listing indicate significant real-world exploitation. The vulnerability is often used as a reconnaissance step in multi-stage attack chains targeting Citrix infrastructure.
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