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Signal

Critical remote code execution vulnerability in F5 BIG-IP APM actively exploited

Evidence first: scan the strongest sources, then decide whether to go deeper.

Published 2026-03-27 18:09 UTCUpdated 2026-03-28 11:48 UTC
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cveexploitssecurity_advisoryincident_responsemalwarethreat_actors
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Evidence trail (top sources)
top sources (4 domains)domains are deduped. counts indicate coverage, not truth.
4 top sources shown
F5 security advisory (AV25-669) - Update 1
Canadian Centre for Cyber Security - Alerts · News · cyber.gc.ca · 2026-03-27 19:56 UTC
View all evidence
Overview

A critical remote code execution vulnerability (CVE-2025-53521) affecting F5 BIG-IP Access Policy Manager (APM) has been actively exploited in the wild. Originally classified as a denial-of-service issue, new information has elevated its severity to RCE with a CVSS v4 score of 9.3.

Entities
F5 NetworksF5BIG-IP Access Policy ManagerBIG-IP APM
Score total
1.99
Momentum 24h
6
Posts
6
Origins
5
Source types
2
Duplicate ratio
0%
Why now
  • New intelligence in March 2026 reclassified the flaw from DoS to critical RCE.
  • CISA's addition of CVE-2025-53521 to the KEV catalog signals active exploitation.
  • Recent advisories and IOCs provide actionable information for defenders to respond promptly.
Why it matters
  • The vulnerability enables unauthenticated remote code execution, posing severe risk to affected systems.
  • Active exploitation means organizations using vulnerable BIG-IP versions face imminent threats.
  • Timely patching and detection are crucial to prevent compromise and data breaches.
LLM analysis
Topic mix: lowPromo risk: lowSource quality: high
Recurring claims
  • CVE-2025-53521 is a critical unauthenticated remote code execution vulnerability in F5 BIG-IP APM actively exploited in the wild
  • F5 has released official patches for multiple BIG-IP product versions to remediate CVE-2025-53521
  • CISA added CVE-2025-53521 to its Known Exploited Vulnerabilities catalog following active exploitation evidence
How sources frame it
  • F5 Networks: neutral
  • The Hacker News: neutral
  • Canadian Centre For Cyber Security: neutral
This critical F5 BIG-IP APM vulnerability has escalated in severity and is actively exploited, highlighting the importance of immediate patching and monitoring.
All evidence
All evidence
Attackers are exploiting RCE vulnerability in BIG-IP APM systems (CVE-2025-53521)
Help Net Security · helpnetsecurity.com · 2026-03-28 09:02 UTC
CISA Adds CVE-2025-53521 to KEV After Active F5 BIG-IP APM Exploitation
The Hacker News · thehackernews.com · 2026-03-28 07:07 UTC
F5 security advisory (AV25-669) - Update 1
Canadian Centre for Cyber Security - Alerts · cyber.gc.ca · 2026-03-27 19:56 UTC
NCSC-2025-0319 [1.01] [M/H] Kwetsbaarheden verholpen in F5 Networks BIG-IP, F5OS en NGINX App Protect WAF
NCSC NL Security Advisories · advisories.ncsc.nl · 2026-03-27 18:09 UTC
Show filters & breakdown
Posts loaded: 0Publishers: 5Origin domains: 5Duplicates: -
Showing 5 / 6
Top publishers (this list)
  • blueteamsec (1)
  • Help Net Security (1)
  • The Hacker News (1)
  • Canadian Centre for Cyber Security - Alerts (1)
  • NCSC NL Security Advisories (1)
Top origin domains (this list)
  • my.f5.com (1)
  • helpnetsecurity.com (1)
  • thehackernews.com (1)
  • cyber.gc.ca (1)
  • advisories.ncsc.nl (1)