Use After Free in F5 nginx Gateway Fabric
CVE-2026-42530
NGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote unauthenticated attacker along with conditions beyond their control can use a specially crafted HTTP/3 session to reopen a QPACK encoder stream. This may cause a Use-after-Free in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Vulnerability class: Use-After-Free
EPSS: 0.038 (89.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- F5 Nginx_gateway_fabric
- F5 Nginx_ingress_controller — versions 4.0.0, 4.0.1
- F5 Nginx_instance_manager
- F5 Nginx Open Source — versions 1.31.0
- F5 Nginx_open_source
Weakness classification (CWE)
Public proof-of-concept exploits
References
- f5sirt@f5.com (vendor-advisory, Vendor Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Third Party Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Third Party Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Third Party Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-42530?
- CVE-2026-42530 is a high-severity vulnerability in F5 nginx Gateway Fabric, classified under Use After Free. CVSS score: 8.1/10. Published 2026-06-17.
- How severe is CVE-2026-42530?
- High severity. CVSS v3 base score is 8.1 out of 10.
- Is CVE-2026-42530 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.