yii2-starter-kit: Active Debug Code
CVE-2026-103475 is a critical-severity active debug code vulnerability in yii2-starter-kit, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected yii2-starter-kit versions: 4.2.0 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.4% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of yii2-starter-kit 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 |
|---|---|---|---|
| Yii2-starter-kit | yii2-starter-kit | 4.2.0 and earlier | 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
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (vulncheck.com) |
| CVSS 3.1 | 9.1 | Critical | CNA (vulncheck.com) |
Official description
yii2-starter-kit through 4.2.0 exposes the Yii debug and Gii modules to all IP addresses by setting allowedIPs to ['*'] in its default development configuration. Unauthenticated remote attackers can access the debug endpoint to read sensitive data including session cookies and database queries, or access the Gii endpoint to generate and write PHP files into the application directory.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Active Debug Code
The product is released with debugging code still enabled or active.
How developers prevent this class of flaw
- Remove debug code before deploying the application.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
References
Other references
Other vulnerabilities in yii2-starter-kit
- 8.8 High severity
Recent Active Debug Code vulnerabilities
- 8.2 High severity
- 9.0 Critical severity
- 7.5 High severity
- 7.0 High severity
- 7.8 High severity
- 8.8 High severity
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