CVE-2026-1642
Medium
Description
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.
SeverityMedium
CVSS5.9
Exploit probability—
Product
F5 Nginx Gateway Fabric
PublishedFeb 4, 2026
First seenFeb 4, 2026
Weakness typeCWE-349CWE-349
How to fix
Update
- f5 nginx_gateway_fabric2.4.1 or later
- f5 nginx_ingress_controller5.3.3 or later
- f5 nginx_open_source1.28.2, 1.29.5 or later
- f5 nginx_plusr35 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| f5 nginx_gateway_fabric | 1.2.0 ≤ v ≤ 1.6.2, 2.0.0 ≤ v < 2.4.1 | 2.4.1 |
| f5 nginx_ingress_controller | 3.4.0 ≤ v ≤ 3.7.2, 4.0.0 ≤ v ≤ 4.0.1, 5.0.0 ≤ v < 5.3.3 | 5.3.3 |
| f5 nginx_instance_manager | 2.15.1 ≤ v ≤ 2.21.0 | — |
| f5 nginx_open_source | 1.3.0 ≤ v < 1.28.2, 1.29.0 ≤ v < 1.29.5 | 1.28.2, 1.29.5 |
| f5 nginx_plus | r33 ≤ v < r35, r32, r33, r34, r35, r36 | r35 |
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