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Nginx Plus CVE-2026-1642

MEDIUM
Acceptance of Extraneous Untrusted Data With Trusted Data (CWE-349)
2026-02-04 f5sirt@f5.com
Nginx Red Hat Nginx Gateway Fabric Nginx Ingress Controller Nginx Instance Manager Nginx Open Source Nginx Plus Suse F5
5.9
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
CWE-349
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V4 - API and Web Service Acceptance of extraneous untrusted data
Impact

CVSS 5.9 (MEDIUM). Attack vector: Network. Complexity: High. Privileges required: None. User interaction: None.
Exploit ScenarioDerived

An attacker could exploit this vulnerability to compromise the affected system.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

NGINX proxy configurations forwarding traffic to upstream TLS servers can be exploited by network-positioned attackers to inject unencrypted data into proxied responses, potentially compromising data integrity. This vulnerability affects NGINX OSS, NGINX Plus, and related products when specific upstream server conditions are present. No patch is currently available for this medium-severity issue.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 21:54 CVSS 5.9

A vulnerability exists in NGINX OSS and NGINX Plus when configured to proxy to upstream Transport Layer Security (TLS) servers. [CVSS 5.9 MEDIUM]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affects your stack

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Technical ContextAI · show details

Affects Nginx Gateway Fabric. 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.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

NVD PRIMARY 5.9 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
SUSE MEDIUM
Red Hat 5.9 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

Lifecycle Timeline

2
Patch released
Apr 09, 2026 - 14:30 nvd
Patch available
CVE Published
Feb 04, 2026 - 15:16 nvd
MEDIUM 5.9

DescriptionCVE.org

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.

Executive ViewAI

Why It Matters

CVE-2026-1642 presents moderate security risk rated CVSS 5.9. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.

Threat Intelligence Overview

EPSS Score
0.0%
Top 97% exploitable
Data Quality
3 sources
Confidence: Low
🇯🇵JVN NVD CVE.org EPSS Vendor

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Low

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Affected Products (CPE)CVE.org

cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_instance_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r32:-:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r32:p1:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r32:p2:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r32:p3:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r33:p1:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r33:p2:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r33:p3:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r34:p1:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r34:p2:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r35:-:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r36:-:*:*:*:*:*:*
+ 1 more

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Same weakness CWE-349 – Acceptance of Extraneous Untrusted Data With Trusted Data

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
SUSE Liberty Linux 8 Fixed
SUSE Liberty Linux 9 Fixed
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Server Applications 15 SP7 Fixed

References

Advisories & patches
ADVISORY https://access.redhat.com/errata/RHSA-2026:3638 ADVISORY https://access.redhat.com/errata/RHSA-2026:4235 ADVISORY https://access.redhat.com/errata/RHSA-2026:4501 ADVISORY https://access.redhat.com/errata/RHSA-2026:4705 ADVISORY https://access.redhat.com/errata/RHSA-2026:4943 ADVISORY https://access.redhat.com/errata/RHSA-2026:5581 ADVISORY https://access.redhat.com/errata/RHSA-2026:5599 ADVISORY https://access.redhat.com/errata/RHSA-2026:6182 ADVISORY https://access.redhat.com/errata/RHSA-2026:6234 ADVISORY https://access.redhat.com/errata/RHSA-2026:6235 ADVISORY https://access.redhat.com/errata/RHSA-2026:6302 ADVISORY https://access.redhat.com/errata/RHSA-2026:6311 ADVISORY https://access.redhat.com/errata/RHSA-2026:6407 ADVISORY https://access.redhat.com/errata/RHSA-2026:6408 ADVISORY https://access.redhat.com/errata/RHSA-2026:6427 ADVISORY https://my.f5.com/manage/s/article/K000159824 ADVISORY https://ubuntu.com/security/notices/USN-8375-1 REF http://www.openwall.com/lists/oss-security/2026/02/05/1

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