High

CVE-2026-55723 — NGINX Ingress Controller vulnerability

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.

Published Jul 15, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: f5

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.5% (30-day exploitation probability)+6
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.51%

ahead of 42% of scored CVEs · Oct 15, 2026

Affects

Nginx Ingress Controller

CVSS base

8.3

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented mitigation — my.f5.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (F5 Nginx Ingress Controller).
Apply the documented mitigations until a definitive fix is available.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
F5	Nginx Ingress Controller	≥ 3.6.0 and ≤ 3.7.2≥ 4.0.0 and ≤ 4.0.1≥ 5.0.0 and < 5.5.2	Vulnerable	NIST National Vulnerability Database
F5	Nginx Ingress Controller	≥ 5.0.0 and < 5.5.2≥ 2026-lts-r1 and < 2026-lts-r3	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

Low

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.7	CVSS 4.0	High	—	—	f5sirt@f5.com via NIST National Vulnerability Database
8.7	CVSS 4.0	High	—	—	f5 via CVE Program (cve.org) e CISA ADP
8.3	CVSS 3.1	High	2.8	5.5	f5sirt@f5.com via NIST National Vulnerability Database
8.3	CVSS 3.1	High	—	—	f5 via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L (score shown at the top: f5sirt@f5.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-76

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · f5/nginx ingress controller
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
Fix documented
Oct 15, 2026 · NIST National Vulnerability Database
CVSS changed · 8.3
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 15, 2026 · f5

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

my.f5.com/manage/s/article/K000161800
Mitigation, Vendor Advisory, vendor-advisory, patch, NIST National Vulnerability Database

Elsewhere on this site

F5
every CVE for this vendor

CWE-76
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-94197 NGINX Ingress Controller vulnerability 2d
High CVE-2026-104939 NGINX Ingress Controller vulnerability 2d
High CVE-2026-77180 NGINX Ingress Controller vulnerability Sep 2, 2026
High CVE-2026-60005 NGINX ngx_http_slice_module vulnerability Jul 15, 2026
Medium CVE-2026-60065 NGINX Plus ngx_stream_mqtt_filter_module vulnerability Jul 15, 2026
Medium CVE-2026-56434 NGINX ngx_http_ssi_module vulnerability Jul 15, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-55723 is "NGINX Ingress Controller vulnerability", rated High. It affects Nginx Ingress Controller (F5); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.3 describes technical severity. EPSS 0.51% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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