NGINX Gateway Fabric: Improper Neutralization of Equivalent Special Elements
CVE-2026-66362 is a high-severity improper neutralization of equivalent special elements vulnerability in NGINX Gateway Fabric from F5, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 2.6.8 as the first without the flaw, so updating NGINX Gateway Fabric to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.57% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update NGINX Gateway Fabric to 2.6.8 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| F5 | NGINX Gateway Fabric | 2.5.0 up to, but not including, 2.6.8 | 2.6.8 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (f5.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.6 | High | CNA (f5.com) |
| CVSS 3.1 | 8.1 | High | CNA (f5.com) |
Official description
Description: When NGINX Plus is configured as the data plane for NGINX Gateway Fabric, an injection vulnerability exists in the NGINX configuration generator component of NGINX Gateway Fabric. User-supplied string values from the Authentication Filter Custom Resource Definition clientID or cookieName fields, or in the clientSecret field of a Secret referenced by an Authentication Filter, are rendered directly into NGINX configuration templates without sanitization or escaping. Impact: An authenticated attacker with permission to create or modify these resources may craft values that inject arbitrary NGINX configuration directives. This is a control plane issue; there is no data plane exposure.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Equivalent Special Elements
The product correctly neutralizes certain special elements, but it improperly neutralizes equivalent special elements.
How developers prevent this class of flaw
- Programming languages and supporting technologies might be chosen which are not subject to these issues.
- Utilize an appropriate mix of allowlist and denylist parsing to filter equivalent special element syntax from all input.
More Improper Neutralization of Equivalent Special Elements vulnerabilities (CWE-76)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in NGINX Gateway Fabric
- 8.8 High severity
- 8.2 High severity
- 8.1 High severity
- 8.1 High severity
- 8.1 High severity
- 8.1 High severity
Recent Improper Neutralization of Equivalent Special Elements vulnerabilities
- 8.3 High severity
- 8.7 High severity
- 8.3 High severity
- 8.4 High severity
- 9.6 Critical severity
- 9.8 Critical severity
Spotted an error? Tell us.