CISA Adds CVE-2025-53521 to Known Exploited Vulnerabilities Catalog

CISA ICS-CERT Advisories

Published March 27th, 2026

Detected March 28th, 2026

Summary

CISA has added CVE-2025-53521, a remote code execution vulnerability in F5 BIG-IP, to its Known Exploited Vulnerabilities (KEV) Catalog. This addition is based on evidence of active exploitation and requires Federal Civilian Executive Branch agencies to remediate the vulnerability.

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What changed

CISA has added CVE-2025-53521, a remote code execution vulnerability affecting F5 BIG-IP, to its Known Exploited Vulnerabilities (KEV) Catalog. This vulnerability has been identified as actively exploited, posing a significant risk to federal networks. The addition is made under Binding Operational Directive (BOD) 22-01, which mandates Federal Civilian Executive Branch (FCEB) agencies to remediate identified vulnerabilities.

FCEB agencies must prioritize the remediation of CVE-2025-53521 by the established due date to protect their networks. While BOD 22-01 specifically applies to FCEB agencies, CISA strongly recommends that all organizations incorporate the remediation of KEV Catalog vulnerabilities into their broader vulnerability management practices to mitigate cyberattack risks.

What to do next

FCEB agencies must remediate CVE-2025-53521 by the due date specified in BOD 22-01.
All organizations should prioritize the remediation of CVE-2025-53521 as part of their vulnerability management practices.

Source document (simplified)

Alert

CISA Adds One Known Exploited Vulnerability to Catalog

Release Date

March 27, 2026

CISA has added one new vulnerability to its Known Exploited Vulnerabilities (KEV) Catalog, based on evidence of active exploitation.

CVE-2025-53521 F5 BIG-IP Remote Code Execution Vulnerability This type of vulnerability is a frequent attack vector for malicious cyber actors and poses significant risks to the federal enterprise.

Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities established the KEV Catalog as a living list of known Common Vulnerabilities and Exposures (CVEs) that carry significant risk to the federal enterprise. BOD 22-01 requires Federal Civilian Executive Branch (FCEB) agencies to remediate identified vulnerabilities by the due date to protect FCEB networks against active threats. See the BOD 22-01 Fact Sheet for more information.

Although BOD 22-01 only applies to FCEB agencies, CISA strongly urges all organizations to reduce their exposure to cyberattacks by prioritizing timely remediation of KEV Catalog vulnerabilities as part of their vulnerability management practice. CISA will continue to add vulnerabilities to the catalog that meet the specified criteria.

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