NukeViet: Path Traversal to Arbitrary File Deletion in Edit Comment Function
Summary
Path Traversal to Arbitrary File Deletion in the Edit Comment admin function. An authenticated administrator can delete arbitrary files within the application root (e.g., config.php) by injecting a crafted attach parameter, rendering the application inoperable.
Affected Component
modules/comment/admin/edit.php
Root Cause
In the vulnerable version, the attach parameter received via HTTP POST was not validated before being processed:
// Vulnerable code (before fix)
$attach = $nv_Request->get_string('attach', 'post', '', true);
if (!empty($attach)) {
$attach = substr($attach, strlen(NV_BASE_SITEURL . NV_UPLOADS_DIR . '/' . $module_upload . '/'));
}
substr() strips the first N characters (equal to the length of the upload URL prefix, e.g. 26 chars for /nukeviet/uploads/comment/). By padding the payload with exactly 26 arbitrary characters followed by a path traversal sequence, an attacker can store ../../ directly into the database.
When the comment is subsequently deleted, del.php reads attach from the database and calls:
nv_deletefile(NV_UPLOADS_REAL_DIR . '/' . $module_upload . '/' . $row['attach']);
nv_deletefile() resolves the path via realpath() and only verifies the result is within NV_ROOTDIR — it does not restrict deletion to the uploads directory — allowing deletion of any file in the installation root.
Steps to Reproduce
- Log in as an administrator and navigate to Admin → Comment Management.
- Select any comment and open the Edit form.
- Intercept the POST request and set the
attach parameter to:
aaaaaaaaaaaaaaaaaaaaaaaaaa../../config.php
*(26 padding characters + traversal path)*
- Submit the request. The value
../../config.php is now stored in the database.
- Delete the comment.
config.php is deleted from the application root.
- The application immediately redirects to the install wizard, confirming the file has been removed.
Impact
- Any file readable by the web server process within
NV_ROOTDIR can be permanently deleted.
- Deleting
config.php causes a full application outage and exposes the install wizard.
Severity
CVSS v3.1 Base Score: 8.7 (High)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:H
| Metric | Value |
|--------|-------|
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | High (Admin required) |
| User Interaction | None |
| Scope | Changed |
| Confidentiality | None |
| Integrity | High |
| Availability | High |
Fix
Added nv_is_file() validation before processing the attach value. This function uses realpath() and a regex check to ensure the file resolves to a path within the intended upload directory, rejecting any traversal attempts.
// Fixed code
$attach = $nv_Request->get_string('attach', 'post', '');
if (!empty($attach) and nv_is_file($attach, NV_UPLOADS_DIR . '/' . $module_upload)) {
$attach = substr($attach, strlen(NV_BASE_SITEURL . NV_UPLOADS_DIR . '/' . $module_upload . '/'));
} else {
$attach = '';
}
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.7): severity, escalated by confirmed exploitation. This CVE's 8.7 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.7 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- Unknown (no EPSS on record)Unknown, not low: FIRST has published no EPSS probability for this CVE.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it