CVE-2026-42238: Nginx-UI is Vulnerable to Unauthenticated Remote Code Execution via Backup Restore

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.8%, percentile 57: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 57% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Only applies if your dependency tree includes github.com/0xJacky/nginx-ui (Go) < 2.3.8, fixed in 2.3.8. Check your lockfile, including transitive dependencies.

What it is

Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.8, nginx-ui exposes a backup restore endpoint (POST /api/restore) that is completely unauthenticated during the first 10 minutes after process startup on any fresh installation. An unauthenticated remote attacker can upload a crafted backup archive that overwrites the application's configuration file (app.ini) and SQLite database. Because the attacker controls the restored app.ini, they can inject an arbitrary OS command into the TestConfigCmd setting. After the application automatically restarts to apply the restored config, a single follow-up request triggers that command as the user running nginx-ui — typically root in Docker deployments. This issue has been patched in version 2.3.8.

From the GitHub advisory

Product: nginx-ui Repository: 0xJacky/nginx-ui (branch: dev) Vulnerability Class: Authentication Bypass → Arbitrary File Write → OS Command Injection Affected Component: POST /api/restore

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1. Vulnerability Summary

nginx-ui exposes a backup restore endpoint (POST /api/restore) that is completely unauthenticated during the first 10 minutes after process startup on any fresh installation. An unauthenticated remote attacker can upload a crafted backup archive that overwrites the application's configuration file (app.ini) and SQLite database. Because the attacker controls the restored app.ini, they can inject an arbitrary OS command into the TestConfigCmd setting. After the application automatically restarts to apply the restored config, a single follow-up request triggers that command as the user running nginx-ui — typically root in Docker deployments.

The 10-minute unauthenticated window resets on every process restart, making this exploitable not only on initial deployments but on any restart event (container restart, upgrade, health-check-triggered restart).

Weakness type: CWE-94.

Product: github.com/0xJacky/nginx-ui (Go) · Assigned by: GitHub_M · Published: 2026-05-04

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: passive

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.83% probability of exploitation activity in the next 30 days; percentile 57.

Timeline

• 2026-05-04 — CVE record published by GitHub_M
• 2026-05-05 — CVE record last updated
• 2026-05-06 — GitHub-reviewed advisory GHSA-4pvg-prr3-9cxr published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-4pvg-prr3-9cxr github.com
2. CVE.org record CVE-2026-42238 cve.org
3. NVD entry CVE-2026-42238 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com

Critical Go advisories · Today’s Security Digest