Attackers are exploiting a critical flaw in F5 BIG-IP Access Policy Manager (APM) that lets them run code on a BIG-IP system without logging in, F5 says. The flaw, CVE-2026-94127, affects only systems in which APM serves as an OAuth authorization server, issuing access tokens to applications. F5 disclosed it in an advisory on September 22 and has released engineering hotfixes.

F5 BIG-IP APM contains a heap-based buffer overflow vulnerability when access policy and an OAuth profile are configured on a virtual server. This vulnerability could allow an unauthenticated attacker to perform remote code execution.

Over 14,000 F5 BIG-IP APM instances remain exposed online, as attackers actively exploit a critical remote code execution flaw CVE-2025-53521. Over 14,000 F5 BIG-IP APM instances remain exposed online, with attackers actively exploiting the critical remote code execution vulnerability CVE-2025-53521 (CVSS ver. 3.1 score of 9.8), the nonprofit security organization Shadowserver warns. The vulnerability in BIG-IP […]

F5 BIG-IP APM flaw CVE-2025-53521 escalates to critical 9.8 RCE, actively exploited. Patch now, check IoCs, and secure vulnerable systems immediately.

CVE-2025-53521 was initially disclosed in October as a high-severity denial-of-service (DoS) flaw, but new information has revealed the bug is actually much more dangerous.

CVE-2025-53521 was initially disclosed in October as a high-severity denial-of-service (DoS) flaw, but new information has revealed the bug is actually much more dangerous.

A critical unauthenticated remote code execution vulnerability (CVE-2025-53521) in F5’s BIG-IP Access Policy Manager (APM) solution is under active exploitation, the US Cybersecurity and Infrastructure Security Agency warned on Friday. CISA added the flaw to its Known Exploited Vulnerabilities catalog after F5 updated the related security advisory, The advisory was initially published on October 15, 2025, when F5 confirmed a data breach that resulted in a “highly sophisticated nation-state threat actor” accessing – among other … More → The post Attackers are exploiting RCE vulnerability in BIG-IP APM systems (CVE-2025-53521) appeared first on Help Net Security .

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds a flaw in F5 BIG-IP AMP to its Known Exploited Vulnerabilities catalog. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added a flaw in F5 BIG-IP AMP, tracked as CVE-2025-53521 (CVSS ver. 3.1 score of 9.8), to its Known Exploited Vulnerabilities (KEV) catalog. The vulnerability in BIG-IP APM allows […]

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added a critical security flaw impacting F5 BIG-IP Access Policy Manager (APM) to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence of active exploitation. The vulnerability in question is CVE-2025-53521 (CVSS v4 score: 9.3), which could allow a threat actor to achieve remote code execution. "When a

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 . 

F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.