What is CVE-2026-42055?

CVE-2026-42055 is a high-severity vulnerability in F5 Nginx Open Source, classified under Heap-based Buffer Overflow. CVSS score: 8.1/10. Published 2026-06-17.

How severe is CVE-2026-42055?

High severity. CVSS v3 base score is 8.1 out of 10.

Buffer overflow in F5 Nginx Open Source

CVE-2026-42055

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, th…

Vulnerability class: Buffer Overflow

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 Open Source — versions 1.13.10, 1.30.2
F5 Nginx Plus — versions 37.0, R36

Weakness classification (CWE)

CWE-122 — Heap-based Buffer Overflow

References

f5sirt@f5.com (vendor-advisory)

Frequently asked questions

What is CVE-2026-42055?: CVE-2026-42055 is a high-severity vulnerability in F5 Nginx Open Source, classified under Heap-based Buffer Overflow. CVSS score: 8.1/10. Published 2026-06-17.
How severe is CVE-2026-42055?: High severity. CVSS v3 base score is 8.1 out of 10.