BL-AC1900: Improper Authentication
CVE-2025-7574 is a critical-severity improper authentication vulnerability in BL-AC1900 from Lb-link, 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 BL-AC1900 versions: 20250702. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.86% chance of exploitation within 30 days, higher than 59% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of BL-AC1900 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 |
|---|---|---|---|
| LB-LINK | BL-AC1900 | 20250702 | Not stated |
| LB-LINK | BL-AC2100_AZ3 | 20250702 | Not stated |
| LB-LINK | BL-AC3600 | 20250702 | Not stated |
| LB-LINK | BL-AX1800 | 20250702 | Not stated |
| LB-LINK | BL-AX5400P | 20250702 | Not stated |
| LB-LINK | BL-WR9000 | 20250702 | 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, which was classified as critical, was found in LB-LINK BL-AC1900, BL-AC2100_AZ3, BL-AC3600, BL-AX1800, BL-AX5400P and BL-WR9000 up to 20250702. Affected is the function reboot/restore of the file /cgi-bin/lighttpd.cgi of the component Web Interface. The manipulation leads to improper authentication. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. 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 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
Other references
Recent Improper Authentication vulnerabilities
- 7.4 High severity
- 6.5 Medium severity
- 7.3 High severity
- 7.6 High severity
- 8.8 High severity
- 8.8 High severity
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