Cyber Resilience

CVE-2026-55723

F5 Nginx Ingress Controller 3.6.0 – 3.7.2

Published
15 July 2026
Modified
16 July 2026
Patch / advisory
View advisory
CVSS Score v4 8.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0029 22th percentile
Risk Priority 38 floored blend · peak EPSS

Summary

CVE-2026-55723 is a high-severity Improper Neutralization of Equivalent Special Elements (CWE-76) vulnerability in F5 Nginx Ingress Controller. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked at the 22th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-76

Related Threats

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-14727Same product: F5 Nginx Ingress Controller
CVE-2026-52865Same product: F5 Nginx Ingress Controller
CVE-2026-56434Same product: F5 Nginx Ingress Controller
CVE-2026-42530Same product: F5 Nginx Ingress Controller
CVE-2026-42533Same product: F5 Nginx Ingress Controller
CVE-2026-60065Same product: F5 Nginx Ingress Controller
CVE-2026-42945Same product: F5 Nginx Ingress Controller
CVE-2026-40701Same product: F5 Nginx Ingress Controller
CVE-2026-42934Same product: F5 Nginx Ingress Controller
CVE-2026-48142Same product: F5 Nginx Ingress Controller

Affected Assets

f5
nginx ingress controller
3.6.0 — 3.7.2 · 4.0.0 — 4.0.1 · 5.0.0 — 5.5.2

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

SA-11 requires developer testing and evaluation that can discover failures to neutralize equivalent special elements.

SI-10 Information Input Validation good match

SI-10 requires validation of information inputs, directly stopping incomplete neutralization of equivalent special elements.

SA-8 Security and Privacy Engineering Principles partial match

SA-8 mandates security engineering principles such as complete input validation and sanitization that cover equivalent special-element forms.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require consistent neutralization of all equivalent special elements during input validation and sanitization.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect incomplete neutralization but does not prevent the weakness itself.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and neutralization of all equivalent special elements.

A.8.26 Application security requirements partial match
prevents

Application security requirements include rules for handling special characters and equivalent encodings.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture principles require consistent canonicalization and neutralization of equivalent inputs.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly address proper neutralization of all equivalent special elements.

References