A800r Firmware: Improper Neutralization of Special Elements used in an OS Command
CVE-2025-28034 is a critical-severity improper neutralization of special elements used in an OS command vulnerability in A800r Firmware 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 A800r Firmware versions: 4.1.2cu.5137_b20200730. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.36% chance of exploitation within 30 days, higher than 72% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of A800r Firmware 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 | A800r Firmware | 4.1.2cu.5137_b20200730 | Not stated |
| TOTOLINK | A810r Firmware | 4.1.2cu.5182_b20201026 | Not stated |
| TOTOLINK | A830r Firmware | 4.1.2cu.5182_b20201102 | Not stated |
| TOTOLINK | A950rg Firmware | 4.1.2cu.5161_b20200903 | Not stated |
| TOTOLINK | A3000ru Firmware | 5.9c.5185_b20201128 | Not stated |
| TOTOLINK | A3100r Firmware | 4.1.2cu.5247_b20211129 | 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
- 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 CISA (ADP).
Official description
TOTOLINK A800R V4.1.2cu.5137_B20200730, A810R V4.1.2cu.5182_B20201026, A830R V4.1.2cu.5182_B20201102, A950RG V4.1.2cu.5161_B20200903, A3000RU V5.9c.5185_B20201128, and A3100R V4.1.2cu.5247_B20211129 were found to contain a pre-auth remote command execution vulnerability in the NTPSyncWithHost function through the hostTime parameter.
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 an OS Command
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before 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.
- For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
- 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.
More Improper Neutralization of Special Elements used in an OS Command vulnerabilities (CWE-78)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Technical write-ups (may include proof of concept)
- locrian-lightning-dc7.notion.site/RCE2-1a98e5e2b1a280bebf53d868f1b1a711?pvs=74Exploit, Third Party Advisory
- locrian-lightning-dc7.notion.site/CVE-2025-28034-RCE2-1a98e5e2b1a280bebf53d868f1b1a711Exploit, Third Party Advisory
Other vulnerabilities in A800r Firmware
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.3 High severity
- 7.3 High severity
- 9.8 Critical severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.1 High severity
- 7.2 High severity
- 9.8 Critical severity
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