N600R: Improper Neutralization of Special Elements used in a Command
CVE-2025-9935 is a critical-severity improper neutralization of special elements used in a command vulnerability in N600R from TOTOLINK, 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. Affected N600R versions: 4.3.0cu.7866_B20220506. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.73% chance of exploitation within 30 days, higher than 86% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of N600R you run against the affected versions below, and install the vendor's latest release.
- 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 |
|---|---|---|---|
| TOTOLINK | N600R | 4.3.0cu.7866_B20220506 | Not stated |
| TOTOLINK | N600r Firmware | 4.3.0cu.7866_b20220506 | 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
- 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 4.0 | 5.5 | Medium | CNA (vuldb.com) |
| CVSS 3.1 | 7.3 | High | CNA (vuldb.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 2.0 | 7.5 | High | CNA (vuldb.com) |
Official description
A vulnerability was determined in TOTOLINK N600R 4.3.0cu.7866_B20220506. This vulnerability affects the function sub_4159F8 of the file /web_cste/cgi-bin/cstecgi.cgi. Executing manipulation can lead to command injection. The attack can be executed remotely. The exploit has been publicly disclosed and may be utilized.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in a Command
The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.
How developers prevent this class of flaw
- If at all possible, use library calls rather than external processes to recreate the desired functionality.
- If possible, ensure that all external commands called from the program are statically created.
- Run time: Run time policy enforcement may be used in an allowlist fashion to prevent use of any non-sanctioned commands.
More Improper Neutralization of Special Elements used in a Command vulnerabilities (CWE-77)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vuldb.com/?id.322337Third Party Advisory, VDB Entry
- vuldb.com/?submit.643088Third Party Advisory, VDB Entry
Technical write-ups (may include proof of concept)
- github.com/mono7s/TOTOLINK/blob/main/N600R/TOTOLINK%20N600R%20Unauthorized_Command_Injection.mdExploit, Third Party Advisory
Other references
- vuldb.com/?ctiid.322337Permissions Required, VDB Entry
- totolink.net/Product
Other vulnerabilities in N600R
- 8.3 High severity
- 10.0 Critical severity
- 8.8 High severity
- 7.2 High severity
- 9.8 Critical severity
Recent Improper Neutralization of Special Elements used in a Command vulnerabilities
- 8.4 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.8 High severity
- 8.4 High severity
- 8.8 High severity
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