CVE-2018-5521

CVE-2018-5521 is a medium-severity vulnerability in F5 Big-ip Application Acceleration Manager with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

• Severity: Medium (CVSS 3.x base score 6.1)
• CVSS v2: 4.3
• EPSS exploit prediction: 1% (56th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-79
• Affected product: F5 Big-ip Application Acceleration Manager
• Published: 2018-06-01
• Last modified: 2026-06-17

Description

On F5 BIG-IP 12.1.0-12.1.3.1, 11.6.1-11.6.3.1, 11.5.1-11.5.5, or 11.2.1, carefully crafted URLs can be used to reflect arbitrary content into GeoIP lookup responses, potentially exposing clients to XSS.

Frequently asked questions

What is CVE-2018-5521?

On F5 BIG-IP 12.1.0-12.1.3.1, 11.6.1-11.6.3.1, 11.5.1-11.5.5, or 11.2.1, carefully crafted URLs can be used to reflect arbitrary content into GeoIP lookup responses, potentially exposing clients to XSS.

How severe is CVE-2018-5521?

CVE-2018-5521 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2018-5521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-5521?

CVE-2018-5521 primarily affects F5 Big-ip Application Acceleration Manager. In total, 26 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-5521?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-5521 published?

CVE-2018-5521 was published on 2018-06-01 and last updated on 2026-06-17.

References

• http://www.securitytracker.com/id/1041021
• https://support.f5.com/csp/article/K23124150

Affected products (26)

• cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_application_acceleration_manager:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_local_traffic_manager:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_advanced_firewall_manager:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_analytics:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_access_policy_manager:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_application_security_manager:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_domain_name_system:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_edge_gateway:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_edge_gateway:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_global_traffic_manager:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_link_controller:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_policy_enforcement_manager:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_webaccelerator:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_webaccelerator:11.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_websafe:*:*:*:*:*:*:*:*
• cpe:2.3:a:f5:big-ip_websafe:11.2.1:*:*:*:*:*:*:*

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