T18-21k Firmware: Improper Neutralization of Special Elements used in a Command
CVE-2026-36741 is a high-severity improper neutralization of special elements used in a command vulnerability in T18-21k Firmware from U-speed, with a CVSS 3.1 base score of 7.2 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. Affected T18-21k Firmware versions: 1.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.09% chance of exploitation within 30 days, higher than 82% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of T18-21k Firmware you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| U-speed | T18-21k Firmware | 1.0 | Not stated |
Version data comes from NVD's product matching. 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
- HighAdministrator-level access is required first.
- 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:H/UI:N/S:U/C:H/I:H/A:H. Scored by CISA (ADP).
Official description
U-SPEED AC1200 Gigabit Wi-Fi Router (Model: T18-21K) V1.0 is vulnerable to Command Injection. The Network Time Protocol (NTP) configuration interface does not properly sanitize user-supplied input. An authenticated user with permission to configure NTP settings can inject arbitrary system commands through crafted input fields. These commands are executed with elevated privileges, leading to potential full system compromise.
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: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- github.com/N0tMilk/vulnerability-researchThird Party Advisory
Technical write-ups (may include proof of concept)
- github.com/N0tMilk/vulnerability-research/tree/main/IoT/CVE-2026-36741Exploit, Third Party Advisory
Recent Improper Neutralization of Special Elements used in a Command vulnerabilities
- 8.7 High severity
- 8.7 High severity
- 8.7 High severity
- 8.8 High severity
- 9.3 Critical severity
- 7.2 High severity
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