CVE-2026-55723Disclosure(f5 / nginx_ingress_controller)

MEDIUMCVSS 8.7 · HIGH

Exploitation ongoing with high activity in latest observed window (3 mentions)

Immediate actions

  • Patch f5 nginx_ingress_controller systems immediately
  • Assume compromise if assets are exposed

Recommended action window: Immediate (within 24h)

NVD 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.

4.0/ 10 priority

Sources & remediation

Vendor / third-party advisories
Weakness type (CWE)
CWE-76

Priority

MEDIUM

Exploitation

ACTIVE

PoC

NONE

Patch

AVAILABLE

Momentum

NONE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

  • nginx_ingress_controller

Threat summary

  • Active exploitation appears in 1 classified signals
  • Patch or workaround signal is available
  • 3 mentions across 1 observed day

What's happening

  • Active exploitation reported across 1 signal
  • Patch or workaround mentioned in 1 signal
  • Technical details provided in 2 signals
  • Disclosure: 2 classified signals
  • 3 total mentions across 1 day

Affected systems

Vendors
Products
nginx_ingress_controller

Deep dive

Activity timeline3 mentions / 1d
01223Mentions · 2026-07-16: 3Active Exploitation · 2026-07-16: 1Patch / Workaround · 2026-07-16: 1Technical Details · 2026-07-16: 207-16
Signal classification2 categories
Disclosure
266.7%
Active Exploitation
133.3%
Referenced assets3 URLs
Full discourse3 posts
  • Cyber Threat Observatory | Alan Turing Institute@TuringCyberObs
    Disclosure

    CVE-2026-55723 F5 NGINX Ingress Controller Ingress configuration injection could let attackers with Kubernetes write access alter NGINX behaviour across hosted services Full analysis: https://github.com/alan-turing-institute/cyber-threat-observatory/blob/main/reports/2026-07-15/TIER_2_CVE-2026-55723.md #CyberSecurity #CloudSecurity #VulnerabilityManagement

    Post summary

    The tweet announces CVE-2026-55723, a configuration injection flaw in the F5 NGINX Ingress Controller that allows Kubernetes users with write access to manipulate NGINX behavior across deployed services, and links to a detailed report for additional information.

    0000166
    58 followersView on X
  • VulDB 🛡@vuldb
    Active Exploitation

    A lot of offensive activities were identified targeting F5 NGINX Ingress Controller (CVE-2026-55723) https://vuldb.com/vuln/379276/cti

    Post summary

    Offensive operations targeting the F5 NGINX Ingress Controller (CVE-2026-55723) have been identified, indicating active exploitation in the wild.

    00000137
    2.3K followersView on X
  • Hugo | DevOps | Cybersecurity 🇱🇻@HugoValters
    Disclosure

    #CVE-2026-55723 - Supply chain attack in #NGINX Ingress Controller via CRD/annotation injection. #CVSS 8.3. No patch yet. Audit configurations and restrict CRD permissions immediately. #CVEAlert #cybersecurity #cybersecuritytips #devops #infosec https://www.valtersit.com/cve/CVE-2026-55723/

    Post summary

    The post announces CVE-2026-55723, a supply chain vulnerability in the NGINX Ingress Controller with a CVSS score of 8.3, noting no patch yet but recommending immediate audit and CRD permission restrictions.

    0000063
    982 followersView on X
CPE platform detail1 entries

1 of 1 entries

PartVendorProductVersionTarget SWTarget HW
Appf5nginx_ingress_controller---

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