F5 BIG-IP Stack-Based Buffer Overflow Vulnerability

F5 BIG-IP

F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution. Added to CISA KEV on 2026-03-27 (federal deadline 2026-03-30).

First seen: 27 Mar 2026
Last update: 27 Mar 2026, 12:00 UTC
Identifiers: CVE-2025-53521
Source: CISA KEV
On the menu as: VPN & firewalls

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## F5 BIG-IP Stack-Based Buffer Overflow Vulnerability
Severity: high, exploited in the wild. Patch status: patched.
Affected: F5 BIG-IP
Ids: CVE-2025-53521

F5 BIG-IP APM contains a stack-based buffer overflow vulnerability that could allow a threat actor to achieve remote code execution. Added to CISA KEV on 2026-03-27 (federal deadline 2026-03-30).

## Steps
1. This touches infrastructure (vpn-edge). Look in terraform, ansible, cloud-init, Dockerfiles and docs for the product and version we run. If it isn't in the repo, say so and list what a human should check on the box.

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2025-53521") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://my.f5.com/manage/s/article/K000160486 https://my.f5.com/manage/s/article/K11438344 https://nvd.nist.gov/vuln/detail/CVE-2025-53521
https://pwned.coffee/i/f5-big-ip-stack-based-buffer-overflow-vulnerability-cve-2025-53521

Sources

Totalone hot coffee