{"id":"CVE-2025-53521","kind":"vulnerability","aliases":["CVE-2025-53521"],"related":[],"title":"f5 big-ip access policy manager: When a BIG-IP APM access policy is configured on a virtual server, specific malicious traffic can lead to Remote…","description":"F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.\n\nCISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","summary":"F5 BIG-IP APM has a stack-based buffer overflow that lets a remote attacker run code on the device. CISA lists it as actively exploited in the wild.","severity":"critical","cvss":9.8,"epss":null,"exploited":true,"exploited_at":"2026-03-27T00:00:00+00:00","products":[{"name":"F5 BIG-IP","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"f5 big-ip access policy manager","fixed":["15.1.10.8"],"affected":">= 15.1.0, < 15.1.10.8","ecosystem":"vendor"},{"name":"f5 big-ip access policy manager","fixed":["16.1.6.1"],"affected":">= 16.1.0, < 16.1.6.1","ecosystem":"vendor"},{"name":"f5 big-ip access policy manager","fixed":["17.1.3"],"affected":">= 17.1.0, < 17.1.3","ecosystem":"vendor"},{"name":"f5 big-ip access policy manager","fixed":["17.5.1.3"],"affected":">= 17.5.0, < 17.5.1.3","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["big-ip-apm","exploited","f5-big-ip","infrastructure"],"not_affected_if":["no-apm-module"],"how_to_check":null,"fix":"Apply the mitigations F5 published for this issue, or discontinue use of the product if mitigations are unavailable (per CISA required action). Exact fixed versions: unknown.","status":"open","published_at":"2025-10-15T14:15:48+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:38:59+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T20:38:59Z","model":"claude-haiku-5-5","output":{"fix":"Apply the mitigations F5 published for this issue, or discontinue use of the product if mitigations are unavailable (per CISA required action). Exact fixed versions: unknown.","reach":"internet","summary":"F5 BIG-IP APM has a stack-based buffer overflow that lets a remote attacker run code on the device. CISA lists it as actively exploited in the wild.","category":"infrastructure","who_cares":["f5-big-ip","big-ip-apm"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Remote attacker runs code on the BIG-IP appliance, exposing traffic and credentials it handles.","analyst_note":"Find F5's advisory for CVE-2025-53521 to get affected and fixed versions, the specific mitigation, and whether APM must be enabled to be exposed.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-apm-module"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000435,"input_tokens":2534,"output_tokens":363,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-01':144C '-2025':30A,33A '-53521':31A,34A '22':143C 'access':5A,14A,43A,50A,57A,64A 'achiev':128C 'action':134C 'activ':103B 'actor':126C 'allow':123C 'apm':13A,70B,81B,112C 'appli':135C 'applic':141C 'attack':93B 'base':86B,117C 'big':3A,11A,37A,41A,48A,55A,62A,68B,74B,79B,110C 'big-ip':2A,10A,36A,40A,47A,54A,61A,78B,109C 'big-ip-apm':67B 'bod':142C 'buffer':87B,118C 'cisa':99B,132C 'cloud':147C 'code':95B,130C 'configur':17A 'contain':113C 'could':122C 'cve':29A,32A 'devic':98B 'discontinu':150C 'execut':131C 'exploit':71B,104B 'f5':1A,35A,39A,46A,53A,60A,73B,77B,108C 'f5-big-ip':72B 'follow':140C 'guidanc':145C 'infrastructur':76B 'instruct':139C 'ip':4A,12A,38A,42A,49A,56A,63A,69B,75B,80B,111C 'lead':26A 'let':90B 'list':100B 'malici':23A 'manag':7A 'manager':45A,52A,59A,66A 'mitig':136C,156C 'overflow':88B,119C 'per':137C 'polici':6A,15A 'policy':44A,51A,58A,65A 'product':154C 'remot':28A,92B,129C 'requir':133C 'run':94B 'server':21A 'servic':148C 'specif':22A 'stack':85B,116C 'stack-bas':84B,115C 'threat':125C 'traffic':24A 'unavail':158C 'use':151C 'vendor':138C 'virtual':20A 'vulner':120C 'wild':107B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2025-10-15T14:15:48+00:00","kev":{"dateAdded":"2026-03-27","dueDate":"2026-03-30","requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"f5sirt@f5.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2025-53521","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-53521","severity":null,"published_at":"2026-03-27T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T13:39:29+00:00","note":null},{"source":"nvd","external_id":"CVE-2025-53521","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-53521","severity":null,"published_at":"2025-10-15T14:15:48+00:00","modified_at":"2026-10-08T12:10:00+00:00","first_seen_at":"2026-10-23T23:44:51+00:00","fetched_at":"2026-10-23T23:44:51+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}