8.8

CVE-2026-84318: Nginx UI: MCP `nginx_config_add` Bypasses Directive Validation — Authenticated RCE

Deferred
AliasesGHSA-9jww-cxg5-rj9mGO-2026-6781
Published 12-10-2026Last modified 13-10-2026

Vulnerability summary

CVE-2026-84318 is a high (CVSS 8.8) Protection Mechanism Failure vulnerability in 0xjacky nginx-ui. EPSS estimates a 0.82% chance of exploitation in the next 30 days, higher than 57.1% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 8.8, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
8.8/10
010
High · v3.1 (NVD)
EPSS score
0.82%
0%100%
Low · Change unavailable
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 12-10-2026
    PublishedVulnerability first disclosed.
  2. 13-10-2026
    Last modifiedVulnerability information updated.

Description

Nginx UI is a web user interface for the Nginx web server. From 2.0.0-rc.6 until 2.4.1, the MCP tool nginx_config_add writes nginx configuration files to disk and triggers an nginx reload without calling config.ValidateConfigFile. The identical flow in the REST API (POST /api/configs) does call that function and correctly rejects dangerous directives. An authenticated attacker can exploit this gap to write config files containing any blocked directive (perl, js_import, load_module, user root, etc.), bypassing nginx-ui's entire security layer. On a server with the nginx Perl, njs, or Lua module loaded, this is post-authentication Remote Code Execution. This issue is fixed in version 2.4.1.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.82%

Chance of exploitation in the next 30 days

Percentile

57%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

13-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

0xjacky1 product
Github.com/0xJacky1 product
  • Nginx-UI≥ 1.9.10-0.20250506154222-1330888280a2, < 1.9.10-0.20260703131214-23d1934099b0

2 vendors · 2 products

References

5 links