AC20: Use of Hard-coded Password
CVE-2025-9091 is a high-severity use of hard-coded password vulnerability in AC20 from Tenda, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected AC20 versions: 16.03.08.12. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.25% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of AC20 you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Tenda | AC20 | 16.03.08.12 | Not stated |
| Tenda | Ac20 Firmware | 16.03.08.12 | 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
- LocalThe attacker needs local access or must trick a user into running something.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 1.1 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 2.5 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 2.0 | 1.0 | Low | CNA (vuldb.com) |
Official description
A security flaw has been discovered in Tenda AC20 16.03.08.12. Affected by this vulnerability is an unknown functionality of the file /etc_ro/shadow. The manipulation leads to hard-coded credentials. It is possible to launch the attack on the local host. The complexity of an attack is rather high. The exploitation appears to be difficult. The exploit has been disclosed to the public and may be used.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Hard-coded Password
The product contains a hard-coded password, which it uses for its own inbound authentication or for outbound authentication to external components.
How developers prevent this class of flaw
- For outbound authentication: store passwords outside of the code in a strongly-protected, encrypted configuration file or database that is protected from access by all outsiders, including other local users on the same system. Properly protect the key (CWE-320). If you cannot use encryption to protect the file, then make sure that the permissions are as restrictive as possible.
- For inbound authentication: Rather than hard-code a default username and password for first time logins, utilize a first login mode that requires the user to enter a unique strong password.
- Perform access control checks and limit which entities can access the feature that requires the hard-coded password. For example, a feature might only be enabled through the system console instead of through a network connection.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vuldb.com/?id.320359Third Party Advisory, VDB Entry
- vuldb.com/?submit.632268Third Party Advisory, VDB Entry
Technical write-ups (may include proof of concept)
- github.com/ZZ2266/.github.io/blob/main/AC20/hardcoded%20password/readme.md#descriptionExploit, Third Party Advisory
- github.com/ZZ2266/.github.io/tree/main/AC20/hardcoded%20password/readme.mdExploit, Third Party Advisory
- github.com/ZZ2266/.github.io/blob/main/AC20/hardcoded%20password/readme.mdExploit, Third Party Advisory
Other references
- vuldb.com/?ctiid.320359Permissions Required, VDB Entry
- tenda.com.cn/Product
Other vulnerabilities in AC20
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
Recent Use of Hard-coded Password vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 8.5 High severity
- 9.8 Critical severity
- 8.6 High severity
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