What is CVE-2026-42934?

CVE-2026-42934 is a medium-severity vulnerability in F5 Nginx Open Source, classified under Out-of-bounds Read. CVSS score: 4.8/10. Published 2026-05-13.

How severe is CVE-2026-42934?

Medium severity. CVSS v3 base score is 4.8 out of 10.

Out-of-bounds Read in F5 Nginx Open Source

CVE-2026-42934

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When charset, source_charset, and charset_map and proxy_pass with disabled buffering ("off") directives are configured, unauthenticated attackers…

Vulnerability class: Buffer Overflow

EPSS: 0.000 (13.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L.

Affected products

F5 Nginx Open Source — versions 1.31.0, 0.3.50
F5 Nginx Plus — versions R37, R36, R32

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

f5sirt@f5.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-42934?: CVE-2026-42934 is a medium-severity vulnerability in F5 Nginx Open Source, classified under Out-of-bounds Read. CVSS score: 4.8/10. Published 2026-05-13.
How severe is CVE-2026-42934?: Medium severity. CVSS v3 base score is 4.8 out of 10.