F5 BIG-IP Stack-Based Buffer Overflow Vulnerability

When a BIG-IP APM access policy is configured on a virtual server, specific malicious traffic can lead to Remote Code Execution (RCE). Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CheckOps priority index

5.6/10 Patch within 7 days

Severity9.3

Probability0.2

Exploitation3/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 2.3% higher than 83.3% of CVEs

CVSS 4.0 9.3 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/

Exploited for 221 days 27 Mar 2026

CISA due date 30 Mar 2026 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 3 / 5

KEV catalog (CISA)27 Mar 2026
Exploited in EUVD (ENISA)27 Mar 2026
Used by ransomwareno
EPSS above 10 %2.3%
No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Affected products

BIG-IP

Affected versions

16.1.0 <16.1.6.1
17.5.0 <17.5.1.3
15.1.0 <15.1.10.8
17.1.0 <17.1.3

Weaknesses (CWE)

CWE-121

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

15 Oct 2025
Published
27 Mar 2026
Exploitation reported (ENISA)
27 Mar 2026
Added to the KEV catalog
30 Mar 2026
CISA remediation due date

References

Other exploited vulnerabilities from the same vendor

CVE-2026-94127F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability
6.9 · Actively exploited
CVE-2023-46748F5 BIG-IP Configuration Utility SQL Injection Vulnerability
4.8 · Background exploitation
CVE-2023-46747F5 BIG-IP Configuration Utility Authentication Bypass Vulnerability
9.8 · Background exploitation
CVE-2022-1388F5 BIG-IP Missing Authentication Vulnerability
9.9 · Background exploitation
CVE-2021-22991F5 BIG-IP Traffic Management Microkernel Buffer Overflow
8.2 · Background exploitation
CVE-2021-22986F5 BIG-IP and BIG-IQ Centralized Management iControl REST Remote Code Execution Vulnerability
9.9 · Background exploitation