Nginx UI: Improper Path Validation Allows Recursive Deletion of the Nginx Configuration Directory

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Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.4, the nginx-ui configuration improperly handles URL-encoded traversal sequences. When specially crafted paths are supplied, the backend resolves them to the base Nginx configuration directory and executes the operation on the base directory (/etc/nginx). In particular, this allows an authenticated user to remove the entire /etc/nginx directory, resulting in a partial Denial of Service. This issue has been patched in version 2.3.4.

Source published

30 Mar 2026 17:59:30 UTC

Source modified

30 Mar 2026 18:37:18 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.4, the nginx-ui configuration improperly handles URL-encoded traversal sequences. When specially crafted paths are supplied, the backend resolves them to the base Nginx configuration directory and executes the operation on the base directory (/etc/nginx). In particular, this allows an authenticated user to remove the entire /etc/nginx directory, resulting in a partial Denial of Service. This issue has been patched in version 2.3.4.

Source published

Mar 30, 2026, 5:59:30 PM (timezone not stated)

Source modified

Mar 30, 2026, 6:37:18 PM (timezone not stated)

Saved here

13 Nov 2026 17:10:07 UTC

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ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.4, the nginx-ui configuration improperly handles URL-encoded traversal sequences. When specially crafted paths are supplied, the backend resolves them to the base Nginx configuration directory and executes the operation on the base directory (/etc/nginx). In particular, this allows an authenticated user to remove the entire /etc/nginx directory, resulting in a partial Denial of Service. This issue has been patched in version 2.3.4.

Source published

30 Mar 2026 18:16:18 UTC

Source modified

17 Jun 2026 10:36:48 UTC

Saved here

25 Oct 2026 08:17:18 UTC

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NIST NVD usage terms; underlying source attribution retained

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CVSS 4.0 · [email protected] · Secondary · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Primary · 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

## Summary The nginx-ui configuration improperly handles URL-encoded traversal sequences. When specially crafted paths are supplied, the backend resolves them to the base Nginx configuration directory and executes the operation on the base directory (/etc/nginx). In particular, this allows an authenticated user to remove the entire `/etc/nginx` directory, resulting in a partial Denial of Service. ## Details The file deletion logic fails to correctly validate and normalize paths containing URL-encoded traversal sequences such as `..%252F`. When such input is processed, the internal path resolution logic attempts to clamp the path into the allowed configuration directory. Instead of rejecting the traversal attempt, the clamping mechanism resolves the path to the base Nginx configuration directory itself. Because the deletion handler invokes `os.RemoveAll`, which recursively removes directories, this results in the deletion of the entire `/etc/nginx` directory. This behavior creates a dangerous interaction between path normalization and deletion logic: - Traversal sequences are not rejected. - Double-encoding (`..%252F`) is used to bypass initial shallow filters. - The clamping mechanism resolves malicious paths to the base configuration directory. - The deletion handler recursively deletes the resolved path. As a result, an attacker can trigger deletion of the entire Nginx configuration directory instead of being blocked by path validation logic. ### Root Cause The vulnerability results from a combination of design flaws: - **Improper Path Canonicalization**: URL-encoded traversal sequences are not properly rejected. - **Unsafe Fallback Logic**: The `GetConfPath` clamping mechanism returns the base configuration directory when traversal is detected instead of rejecting the request. - **Unsafe Deletion Primitive**: The deletion handler invokes `os.RemoveAll`, which recursively deletes directories without additional safeguards. (delete.go) ``` // Delete the file or directory err = os.RemoveAll(fullPath) if err != nil { cosy.ErrHandler(c, err) return } ``` This interaction causes the deletion operation to target the most sensitive directory when a traversal attempt occurs. ### Environment - **Server OS**: Kali Linux 6.17.10-1kali1 (6.17.10+kali-amd64) - **Nginx UI Version**: nginx-ui v2.3.3 - **Deployment**: Docker / Default installation ## Proof of Concept ### Steps to Reproduce 1. Log into nginx-ui. 2. Go to Manage Configs and create a Folder named *..%252F..%252F..%252F..%252Ftest* <img width="1608" height="559" alt="image" src="https://github.com/user-attachments/assets/738d7d65-7e13-48fa-affc-d5509c43900f" /> 3. Observe that the backend resolves the path to /etc/nginx.. 4. Now lets create a file called *testing*. 5. Save it and rename it to *..%252F..%252F..%252F..%252Ftest* (It is not possible to create it directly with the payload name so we have to rename it) 6. Go back to manage configs and Click Delete to remove the file we just created. 7. Check that there is an error: <img width="1578" height="696" alt="image" src="https://github.com/user-attachments/assets/51a36310-0676-4fe5-b80c-e0199498efbf" /> 8. Reload the website and check that the /etc/nginx folder has been completely removed: <img width="1313" height="722" alt="image" src="https://github.com/user-attachments/assets/0a9ddd1b-786b-4cf2-8abd-1dc6f3a77807" /> ## Impact An authenticated user capable of invoking the configuration deletion endpoint can trigger the recursive deletion of the entire Nginx configuration directory (`/etc/nginx`). This results in: - Immediate failure of the Nginx service due to missing configuration files. - Loss of all Nginx configuration managed by nginx-ui. - Denial of Service for all web services relying on the affected Nginx instance. As the deletion operation uses a recursive filesystem call, the entire configuration directory is removed, leaving the system unable to restart Nginx until the configuration is manually restored. A patched version is available at https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.4.

Source published

30 Mar 2026 16:33:00 UTC

Source modified

10 Sep 2026 03:51:00 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Publisher rating · MODERATE

Nginx Configuration Directory Vulnerable to Recursive Deletion via Improper Path Validation in github.com/0xJacky/Nginx-UI

Source published

2 Apr 2026 18:42:30 UTC

Source modified

2 Apr 2026 21:20:06 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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OSV · upstream source license applies

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Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.