CVE-2026-55723: CWE-76 Improper Neutralization of Equivalent Special Elements in F5 NGINX Ingress Controller
When NGINX Ingress Controller is configured with Custom Resource Definitions (CRDs) or Ingress annotations, an injection vulnerability exists in the configuration generator of NGINX Ingress Controller. Multiple user-controllable fields are written into the generated NGINX configuration without sanitization. An authenticated attacker with permission to create or modify these CRDs or annotations may craft values that inject arbitrary NGINX configuration directives. Impact: An authenticated attacker granted write access to NGINX Ingress Controller CRDs or Ingress annotations through the Kubernetes API may be able to inject arbitrary NGINX configuration directives, create or delete files, or disable services. There is no data plane exposure; this is a control plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
AI Analysis
Technical Summary
The vulnerability arises because multiple user-controllable fields are written into the generated NGINX configuration without proper sanitization, allowing an authenticated attacker with write permissions on CRDs or Ingress annotations via the Kubernetes API to inject arbitrary NGINX directives. This can lead to creation or deletion of files or disabling services within the control plane. The issue is limited to the control plane and does not expose the data plane directly. The affected versions explicitly include 5.0.0 and 2026-lts-r1. No official patch or remediation level has been provided at the time of this report.
Potential Impact
An attacker with authenticated write access to NGINX Ingress Controller CRDs or Ingress annotations can inject arbitrary configuration directives, potentially leading to unauthorized file creation or deletion and service disruption. The impact is high on confidentiality and integrity, with limited availability impact. There is no direct exposure of the data plane, so exploitation requires control plane access.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict write permissions to CRDs and Ingress annotations to trusted users only to limit the risk of exploitation.
CVE-2026-55723: CWE-76 Improper Neutralization of Equivalent Special Elements in F5 NGINX Ingress Controller
Description
When NGINX Ingress Controller is configured with Custom Resource Definitions (CRDs) or Ingress annotations, an injection vulnerability exists in the configuration generator of NGINX Ingress Controller. Multiple user-controllable fields are written into the generated NGINX configuration without sanitization. An authenticated attacker with permission to create or modify these CRDs or annotations may craft values that inject arbitrary NGINX configuration directives. Impact: An authenticated attacker granted write access to NGINX Ingress Controller CRDs or Ingress annotations through the Kubernetes API may be able to inject arbitrary NGINX configuration directives, create or delete files, or disable services. There is no data plane exposure; this is a control plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
CVSS v3.1
Score 8.3high
Affected software
pkg:github/f5/nginx-ingress-controllerRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability arises because multiple user-controllable fields are written into the generated NGINX configuration without proper sanitization, allowing an authenticated attacker with write permissions on CRDs or Ingress annotations via the Kubernetes API to inject arbitrary NGINX directives. This can lead to creation or deletion of files or disabling services within the control plane. The issue is limited to the control plane and does not expose the data plane directly. The affected versions explicitly include 5.0.0 and 2026-lts-r1. No official patch or remediation level has been provided at the time of this report.
Potential Impact
An attacker with authenticated write access to NGINX Ingress Controller CRDs or Ingress annotations can inject arbitrary configuration directives, potentially leading to unauthorized file creation or deletion and service disruption. The impact is high on confidentiality and integrity, with limited availability impact. There is no direct exposure of the data plane, so exploitation requires control plane access.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict write permissions to CRDs and Ingress annotations to trusted users only to limit the risk of exploitation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- f5
- Date Reserved
- 2026-06-17T23:45:50.277Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a579dce68715ace43e953d2
Added to database: 07/15/2026, 14:48:46 UTC
Last enriched: 07/15/2026, 15:04:45 UTC
Last updated: 07/15/2026, 16:03:40 UTC
Views: 3
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