AC8: Improper Authentication
CVE-2026-4252 is a critical-severity improper authentication vulnerability in AC8 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 AC8 versions: 16.03.50.11. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.43% chance of exploitation within 30 days, higher than 74% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of AC8 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 | AC8 | 16.03.50.11 | Not stated |
| Tenda | Ac8 Firmware | 16.03.50.11 | 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 CNA (vuldb.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.9 | High | CNA (vuldb.com) |
| CVSS 3.1 | 9.8 | Critical | CNA (vuldb.com) |
| CVSS 2.0 | 10.0 | High | CNA (vuldb.com) |
Official description
A vulnerability was identified in Tenda AC8 16.03.50.11. Affected by this issue is the function check_is_ipv6 of the component IPv6 Handler. The manipulation leads to reliance on ip address for authentication. It is possible to initiate the attack remotely. The exploit is publicly available and might be used.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
How developers prevent this class of flaw
- Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
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
Third-party and government advisories
- vuldb.com/?id.351210Third Party Advisory, VDB Entry
Technical write-ups (may include proof of concept)
- github.com/digitalandrew/tenda_ac8_v5/blob/main/poc_ipv6_auth_bypass.pyExploit
- vuldb.com/?submit.771759Exploit, Third Party Advisory, VDB Entry
Other references
- vuldb.com/?ctiid.351210Permissions Required, VDB Entry
- tenda.com.cn/Product
Other vulnerabilities in AC8
- 9.8 Critical severity
- 7.2 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
Recent Improper Authentication vulnerabilities
- 7.1 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
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