AC500: Improper Neutralization of Special Elements used in a Command
CVE-2024-3908 is a critical-severity improper neutralization of special elements used in a command vulnerability in AC500 from Tenda, 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 AC500 versions: 2.0.1.9(1307). The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 8.72% chance of exploitation within 30 days, which is in the top 4.78% of all scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of AC500 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 |
|---|---|---|---|
| Tenda | AC500 | 2.0.1.9(1307) | Not stated |
| Tenda | Ac500 Firmware | 2.0.1.9\(1307\) | 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 3.1 | 6.3 | Medium | CNA (vuldb.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 2.0 | 6.5 | Medium | CNA (vuldb.com) |
Official description
A vulnerability classified as critical has been found in Tenda AC500 2.0.1.9(1307). Affected is the function formWriteFacMac of the file /goform/WriteFacMac. The manipulation of the argument mac leads to command injection. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The identifier of this vulnerability is VDB-261144. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.
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: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vuldb.com/?id.261144Third Party Advisory, VDB Entry
- vuldb.com/?submit.313803Third Party Advisory, VDB Entry
Technical write-ups (may include proof of concept)
- github.com/abcdefg-png/IoT-vulnerable/blob/main/Tenda/AC500/formWriteFacMac.mdExploit, Third Party Advisory
Other references
- vuldb.com/?ctiid.261144Permissions Required, VDB Entry
Other vulnerabilities in AC500
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Improper Neutralization of Special Elements used in a Command vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 9.1 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
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