CyberSecBulletin
CVE-2023-33177NVD status: Modified

xibo-cms: Improper Limitation of a Pathname to a Restricted Directory

CVE-2023-33177 is a high-severity improper limitation of a pathname to a restricted directory vulnerability in xibo-cms from Xibosignage, with a CVSS 3.1 base score of 8.8 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. Affected xibo-cms versions: >= 1.8.0, < 2.3.17; >= 3.0.0, < 3.3.5. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 7.04% chance of exploitation within 30 days, which is in the top 5.72% of all scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Xibo to 2.3.17 or 3.3.5, whichever matches your release line, or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Xibosignagexibo-cms>= 1.8.0, < 2.3.17; >= 3.0.0, < 3.3.5Not stated
XibosignageXibo1.8.0 up to, but not including, 2.3.17; 3.0.0 up to, but not including, 3.3.52.3.17, 3.3.5

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
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCNA (github.com)
CVSS 3.18.8HighNVD

Official description

Xibo is a content management system (CMS). A path traversal vulnerability exists in the Xibo CMS whereby a specially crafted zip file can be uploaded to the CMS via the layout import function by an authenticated user which would allow creation of files outside of the CMS library directory as the webserver user. This can be used to upload a PHP webshell inside the web root directory and achieve remote code execution as the webserver user. Users should upgrade to version 2.3.17 or 3.3.5, which fix this issue. Customers who host their CMS with Xibo Signage have already received an upgrade or patch to resolve this issue regardless of the CMS version that they are running.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Limitation of a Pathname to a Restricted Directory

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

How developers prevent this class of flaw

  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
  • Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.

More Improper Limitation of a Pathname to a Restricted Directory vulnerabilities (CWE-22)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in xibo-cms

All xibo-cms vulnerabilities

Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities

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