Microsoft Internet Security and Acceleration (ISA) Server 2006 Gold and SP1, when Radius OTP is enabled, uses the HTTP-Basic authentication method, which allows remote attackers to gain the privileges of an arbitrary account, and access published web pages, via vectors involving attempted access to a network resource behind the ISA Server, aka "Radius OTP Bypass Vulnerability."
Conclusion & alert: CVE-2009-1135 is rated High Risk (68.3/100): CVSS Critical severity, with high exploitation likelihood (EPSS 39.38%, 97th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2025-05-30 | 41.10% | 39.38% | -1.72% |
| 2 | 2025-03-30 | 40.51% | 41.10% | +0.60% |
| 3 | 2025-03-29 | — | 40.51% | — |
Full EPSS history (13 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 9.0 | 2.0 | HIGH |
|
8.0 | 10.0 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| microsoft | isa_server | 2006 | cpe:2.3:a:microsoft:isa_server:2006:*:*:*:*:*:*:* |
| microsoft | isa_server | 2006 | cpe:2.3:a:microsoft:isa_server:2006:sp1:*:*:*:*:*:* |
| microsoft | isa_server | 2006 | cpe:2.3:a:microsoft:isa_server:2006:supportability:*:*:*:*:*:* |