F5 BIG-IP APM: attackers can run their own code
OFFICIAL NAME: F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability
WHAT IT IS · VPN, FIREWALL OR GATEWAYIt sits at the edge of your network and faces the internet, so attackers can reach it directly.
DO THIS FIRSTIf you have it, patch it today. If you cannot, block access to it from the internet until you can. Not sure if you use it? Send this page to your IT provider or security lead and ask.
TECHNICAL SUMMARY 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.
WHY THIS VERDICT Attacks are confirmed. The vulnerability is 49 days old, so many systems are likely still unpatched. It affects a product that faces the internet or gives remote access. The severity score is critical (9.3).
WHY IT RANKS HERE Exploitation is confirmed by an authoritative source. The product faces the internet or gives remote access.
- HIGHEST CONFIRMED RUNG
- EXPLOITED
- CISA KEV
- LISTED
- EXPLOIT CODE
- PROOF OF CONCEPT
How far has it climbed?
01 TALK
□ NO EVIDENCE YETNEWEST EVIDENCE NONE YETNo evidence yet.
SRC: NONE YET02 EXPOSED
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETWe have no source that counts exposed systems yet. Internet scan data needs a partnership we do not have. No evidence here does not mean nothing is exposed.
03 TRIED
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESAttacks that worked are confirmed (step 4), so attempts count as confirmed too.
04 EXPLOITED
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESCISA Vulnrichment marks CVE-2026-94127 as actively exploited. 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.
05 DAMAGE
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETBreach notices and filings rarely name the flaw that was used, so we cannot link them to this event yet. No evidence here does not mean no harm.
When each thing happened
- DISCLOSED
- EXPLOIT CODE PUBLIC
- FIRST ATTACK REPORT
- CISA KEV LISTING
- US FEDERAL DEADLINE
THE FIX
CISA's instruction: apply the vendor's fix, or stop using the product if no fix exists. The deadline CISA set for US federal agencies, Sep 25, 2026, has passed. It is a US government deadline; use it as a guide.
Questions to ask this week
- Do we run F5 BIG-IP APM? If yes, is it patched or cut off from the internet?
- Who owns fixing it, and by what date?
- Have we checked for signs of attack since the first report, not just since the patch?
How it unfolded
- Attack activity. SEP 21, 2026F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability
- Attack activity. SEP 22, 2026CISA Vulnrichment marks CVE-2026-94127 as actively exploited
- SEP 23, 20262 public GitHub repositories claim a proof of concept for CVE-2026-94127
- SEP 24, 2026Vulnerability CVE-2026-94127 confirmed by a researcher (CIRCL sighting)
SOURCES
- [1] CIRCL Vulnerability-Lookup sightings: Vulnerability CVE-2026-94127 confirmed by a researcher (CIRCL sighting), SEP 24
- [2] PoC-in-GitHub: 2 public GitHub repositories claim a proof of concept for CVE-2026-94127, SEP 23
- [3] CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-94127 as actively exploited, SEP 22
- [4] CISA Known Exploited Vulnerabilities: F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability, SEP 21