CYBERSECURITYMarch 28, 20261 min read13 views

CISA Adds CVE-2025-53521 to KEV After Active F5 BIG-IP APM Exploitation

CISA has added a critical F5 BIG-IP APM vulnerability (CVE-2025-53521) to its Known Exploited Vulnerabilities catalog following evidence of active exploitation and its reclassification as a remote code execution flaw.

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. While the shortcoming was initially categorized and remediated as a denial-of-service (DoS) vulnerability with a CVSS v4 score of 8.7, F5 said it has been reclassified as a case of RCE in light of new information obtained in March 2026. The company has since updated its advisory to confirm that the vulnerability has been exploited in the vulnerable BIG-IP versions. F5 published a number of indicators that can be used to assess if the system has been compromised, including file-related indicators, log-related indicators, and other observed TTPs such as in-memory webshells and disguised HTTP traffic. The issue impacts versions 17.5, 17.1, 16.1, and 15.1. Federal agencies have been given until March 30, 2026, to apply the fixes. Security experts have noted acute scanning activity for vulnerable devices following the CISA announcement.

Source: The Hacker News

More in this category

cybersecurity

FakeGit Campaign Uses 7,600 GitHub Repositories to Spread SmartLoader Malware

Cybersecurity researchers have uncovered a massive campaign named FakeGit, leveraging thousands of malicious GitHub repositories to distribute SmartLoader malware. The campaign features a novel technique called AgentBaiting, which tricks AI agents into executing malicious instructions autonomously.

cybersecurity

OpenSSL HollowByte Flaw Could Freeze Server Memory with 11-Byte TLS Requests

A mere 11-byte TLS request can force an unpatched OpenSSL server to allocate up to 131 KB of memory that is never released. OpenSSL silently patched this "HollowByte" vulnerability without issuing a CVE or security advisory.

cybersecurity

Seven Malicious Vite npm Packages Use Blockchain C2 to Deliver a RAT

Cybersecurity researchers have discovered a cluster of seven malicious npm packages targeting the Vite frontend tooling ecosystem as part of a software supply chain attack.

cybersecurity

GoldenEyeDog Subgroup Linked to DigiCert Breach and Code-Signing Certificate Theft

Cybersecurity researchers have attributed the April 2026 DigiCert security incident to CylindricalCanine, a subgroup of the Chinese cybercrime group GoldenEyeDog, which compromised DigiCert's support portal to steal and abuse code-signing certificates.

cybersecurity

Armenia Detains Russian Tourist on U.S. Warrant for REvil Hacker, Lawyers Say Wrong Man

Armenia has detained a Russian tourist on a U.S. extradition warrant targeting a REvil ransomware suspect. However, defense lawyers argue it is a case of mistaken identity caused by incomplete name details in the U.S. warrant.

cybersecurity

ACR Stealer Uses ClickFix Lures to Steal Browser Tokens and Microsoft 365 Files

ACR Stealer, an active infostealer, is targeting enterprise networks using sophisticated 'ClickFix' social engineering lures. By tricking users into pasting malicious commands into the Run dialog, attackers can easily steal session tokens, browser credentials, and sensitive documents from OneDrive and SharePoint.