My Cloud Home and My Cloud Home Duo: Improper Limitation of a Pathname to a Restricted Directory
CVE-2022-36327 is a critical-severity improper limitation of a pathname to a restricted directory vulnerability in My Cloud Home and My Cloud Home Duo from Western Digital, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 9.4.0-191 as the first without the flaw, so updating My Cloud Home and My Cloud Home Duo to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.47% chance of exploitation within 30 days, higher than 74% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update My Cloud Home and My Cloud Home Duo to 9.4.0-191 or a later version.
- Update ibi to 9.4.0-191 or a later version.
- Update My Cloud OS 5 to 5.26.202 or a later version.
- Read the advisory on westerndigital.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Western Digital | My Cloud Home and My Cloud Home Duo | before 9.4.0-191 | 9.4.0-191 |
| SanDisk | ibi | before 9.4.0-191 | 9.4.0-191 |
| Western Digital | My Cloud OS 5 | before 5.26.202 | 5.26.202 |
| Westerndigital | My Cloud Home Firmware | before 9.4.0-191 | 9.4.0-191 |
| Westerndigital | Sandisk Ibi Firmware | before 9.4.0-191 | 9.4.0-191 |
| Westerndigital | My Cloud Home Duo Firmware | before 9.4.0-191 | 9.4.0-191 |
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
- NoneNo account or login is needed.
- 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:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.8 | Medium | CNA (wdc.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability that could allow an attacker to write files to locations with certain critical filesystem types leading to remote code execution was discovered in Western Digital My Cloud Home, My Cloud Home Duo, SanDisk ibi and Western Digital My Cloud OS 5 devices. This issue requires an authentication bypass issue to be triggered before this can be exploited. This issue affects My Cloud Home and My Cloud Home Duo: before 9.4.0-191; ibi: before 9.4.0-191; My Cloud OS 5: before 5.26.202.
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
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in My Cloud Home and My Cloud Home Duo
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 7.5 High severity
- 9.1 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.8 High severity
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