F5 flaws being used in attacks

CISA lists 8 flaws in F5 products as being used in attacks, most recently on 22 Sep 2026. 4 have been used in ransomware.

What to do

1. Update every F5 product you use.Install the updates F5 offers, on every device, and restart when asked. Each flaw below has a fix or clear advice; that’s one of CISA’s conditions for listing it.
2. If someone looks after IT for you, send them this page.Many of these are in equipment you don’t see: routers, firewalls, servers, the office network. Ask them to confirm each one is fixed, or that you don’t use the product.
3. Check anything else in the lookup.Search any app, company or CVE. Not being on CISA’s list doesn’t mean safe: keep updating either way.

Every flaw, newest first

1. Being used in attacksAdded by CISA on 22 Sep 2026
   F5 BIG-IP APM
   CVE-2026-94127F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability
   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.
   CISA’s required actionApply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Read all

   Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
   CVE recordNVD
2. Being used in attacksAdded by CISA on 27 Mar 2026
   F5 BIG-IP
   CVE-2025-53521F5 BIG-IP Stack-Based Buffer Overflow Vulnerability
   F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution.
   CISA’s required actionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
   CVE recordNVD
3. Being used in attacksAdded by CISA on 31 Oct 2023
   F5 BIG-IP Configuration Utility
   CVE-2023-46748F5 BIG-IP Configuration Utility SQL Injection Vulnerability
   F5 BIG-IP Configuration utility contains an SQL injection vulnerability that may allow an authenticated attacker with network access through the BIG-IP management port and/or self IP addresses to execute system commands. This vulnerability can be used in conjunction with CVE-2023-46747.
   CISA’s required actionApply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
   CVE recordNVD
4. Being used in attacksUsed in ransomwareAdded by CISA on 31 Oct 2023
   F5 BIG-IP Configuration Utility
   CVE-2023-46747F5 BIG-IP Configuration Utility Authentication Bypass Vulnerability
   F5 BIG-IP Configuration utility contains an authentication bypass using an alternate path or channel vulnerability due to undisclosed requests that may allow an unauthenticated attacker with network access to the BIG-IP system through the management port and/or self IP addresses to execute system commands. This vulnerability can be used in conjunction with CVE-2023-46748.
   CISA’s required actionApply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
   CVE recordNVD
5. Being used in attacksUsed in ransomwareAdded by CISA on 10 May 2022
   F5 BIG-IP
   CVE-2022-1388F5 BIG-IP Missing Authentication Vulnerability
   F5 BIG-IP contains a missing authentication in critical function vulnerability which can allow for remote code execution, creation or deletion of files, or disabling services.
   CISA’s required actionApply updates per vendor instructions.
   CVE recordNVD
6. Being used in attacksAdded by CISA on 18 Jan 2022
   F5 BIG-IP Traffic Management Microkernel
   CVE-2021-22991F5 BIG-IP Traffic Management Microkernel Buffer Overflow
   The Traffic Management Microkernel of BIG-IP ASM Risk Engine has a buffer overflow vulnerability, leading to a bypassing of URL-based access controls.
   CISA’s required actionApply updates per vendor instructions.
   CVE recordNVD
7. Being used in attacksUsed in ransomwareAdded by CISA on 3 Nov 2021
   F5 BIG-IP and BIG-IQ Centralized Management
   CVE-2021-22986F5 BIG-IP and BIG-IQ Centralized Management iControl REST Remote Code Execution Vulnerability
   F5 BIG-IP and BIG-IQ Centralized Management contain a remote code execution vulnerability in the iControl REST interface that allows unauthenticated attackers with network access to execute system commands, create or delete files, and disable services.
   CISA’s required actionApply updates per vendor instructions.
   CVE recordNVD
8. Being used in attacksUsed in ransomwareAdded by CISA on 3 Nov 2021
   F5 BIG-IP
   CVE-2020-5902F5 BIG-IP Traffic Management User Interface (TMUI) Remote Code Execution Vulnerability
   F5 BIG-IP Traffic Management User Interface (TMUI) contains a remote code execution vulnerability in undisclosed pages.
   CISA’s required actionApply updates per vendor instructions.
   CVE recordNVD

From CISA’s Known Exploited Vulnerabilities catalog, updated 21 Oct 2026 (version 2026.10.21). CISA’s required actions are written for US government agencies. F5 on CISA’s site.