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.

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact High

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00011.

Exploitation none

Automatable no

Technical Impact partial

Affected Vendors & Products

Vendors Products
F5 Subscribe
Nginx Open Source Subscribe
Nginx Plus Subscribe

No data.

No data.

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Vendors Products
F5 Subscribe
Nginx Open Source Subscribe
Nginx Plus Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
http://www.openwall.com/lists/oss-security/2026/02/05/1 cve-icon
https://my.f5.com/manage/s/article/K000159824 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-1642 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-1642 cve-icon
History

Thu, 05 Feb 2026 06:30:00 +0000

Type Values Removed Values Added
References

Thu, 05 Feb 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Moderate

Wed, 04 Feb 2026 21:30:00 +0000

Type Values Removed Values Added
First Time appeared F5
F5 nginx Open Source
F5 nginx Plus
Vendors & Products F5
F5 nginx Open Source
F5 nginx Plus

Wed, 04 Feb 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 04 Feb 2026 15:15:00 +0000

Type Values Removed Values Added
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.
Title NGINX vulnerability
Weaknesses CWE-349
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N'}

cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: f5

Published:

Updated: 2026-02-05T05:25:39.303Z

Reserved: 2026-01-29T18:26:26.996Z

Link: CVE-2026-1642

cve-icon Vulnrichment

Updated: 2026-02-05T05:25:39.303Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2026-02-04T15:16:14.190

Modified: 2026-02-05T06:15:53.893

Link: CVE-2026-1642

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-02-04T15:02:06Z

Links: CVE-2026-1642 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-02-04T21:17:45Z

Weaknesses