N200RE V5: Use of Externally-Controlled Format String
CVE-2023-4746 is a high-severity use of externally-controlled format string vulnerability in N200RE V5 from TOTOLINK, 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 N200RE V5 versions: 9.3.5u.6437_B20230519. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 3.71% chance of exploitation within 30 days, higher than 90% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of N200RE V5 you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TOTOLINK | N200RE V5 | 9.3.5u.6437_B20230519 | Not stated |
| TOTOLINK | N200re-v5 Firmware | 9.3.5u.6437_b20230519 | Not stated |
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 system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA (vuldb.com) |
| CVSS 3.1 | 8.8 | High | NVD |
| CVSS 2.0 | 9.0 | High | CNA (vuldb.com) |
Official description
A vulnerability classified as critical has been found in TOTOLINK N200RE V5 9.3.5u.6437_B20230519. This affects the function Validity_check. The manipulation leads to format string. It is possible to initiate the attack remotely. The root-cause of the vulnerability is a format string issue. But the impact is to bypass the validation which leads to to OS command injection. The exploit has been disclosed to the public and may be used. The associated identifier of this vulnerability is VDB-238635.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Externally-Controlled Format String
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
How developers prevent this class of flaw
- Choose a language that is not subject to this flaw.
- Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings.
- Run compilers and linkers with high warning levels, since they may detect incorrect usage.
More Use of Externally-Controlled Format String vulnerabilities (CWE-134)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vuldb.com/?id.238635Third Party Advisory
Technical write-ups (may include proof of concept)
- gist.github.com/dmknght/8f3b6aa65e9d08f45b5236c6e9ab8d80Exploit, Third Party Advisory
Other references
- vuldb.com/?ctiid.238635Permissions Required
Recent Use of Externally-Controlled Format String vulnerabilities
- 9.8 Critical severity
- 7.2 High severity
- 8.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
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