What is CVE-2026-1642?

CVE-2026-1642 is a medium-severity vulnerability in F5 Nginx Open Source, classified under CWE-349. CVSS score: 5.9/10. Published 2026-02-04.

How severe is CVE-2026-1642?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in F5 Nginx Open Source

CVE-2026-1642

A vulnerability exists in NGINX OSS and NGINX Plus when configured to proxy to upstream Transport Layer Security (TLS) servers. An attacker with a man-in-the-middle (MITM) position on the upstream server side—along with conditions beyond t…

EPSS: 0.000 (5.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.

Affected products

F5 Nginx Open Source — versions 1.3.0
F5 Nginx Plus — versions R36, R35, R34

Weakness classification (CWE)

CWE-349

References

my.f5.com/manage/s/article/K000159824 (vendor-advisory)

Frequently asked questions

What is CVE-2026-1642?: CVE-2026-1642 is a medium-severity vulnerability in F5 Nginx Open Source, classified under CWE-349. CVSS score: 5.9/10. Published 2026-02-04.
How severe is CVE-2026-1642?: Medium severity. CVSS v3 base score is 5.9 out of 10.