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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.

PUBLISHED Reserved 2026-01-29 | Published 2026-02-04 | Updated 2026-02-05 | Assigner f5




MEDIUM: 5.9CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

HIGH: 8.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Problem types

CWE-349: Acceptance of Extraneous Untrusted Data With Trusted Data

Product status

Default status
unknown

1.3.0 (semver) before 1.29.5
affected

Default status
unknown

R36 (custom) before R36 P2
affected

R35 (custom) before R35 P1
affected

R34 (custom) before *
affected

R33 (custom) before *
affected

R32 (custom) before R32 P4
affected

Credits

F5 finder

References

www.openwall.com/lists/oss-security/2026/02/05/1

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

cve.org (CVE-2026-1642)

nvd.nist.gov (CVE-2026-1642)

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