Vulnerability in F5 nginx Gateway Fabric
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 the attacker's control—may be able to inject plain text data into the response from an upstream proxied server. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.004 (31.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 31.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000
Affected products
- F5 nginx Gateway Fabric
- F5 nginx Ingress Controller
- F5 nginx Instance Manager
- F5 nginx Open Source — versions 1.3.0
- F5 nginx Open Source
- F5 nginx Plus — versions R36, R35, R34
- F5 nginx Plus — versions r32, r33, r34
Weakness classification (CWE)
References
- my.f5.com/manage/s/article/K000159824 (vendor-advisory, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-1642?
- CVE-2026-1642 is a medium-severity vulnerability in F5 nginx Gateway Fabric, 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.