Multiple buffer overflows in RealNetworks Helix Server and Helix Mobile Server 11.x before 11.1.8 and 12.x before 12.0.1 allow remote attackers to (1) cause a denial of service via three crafted RTSP SETUP commands, or execute arbitrary code via (2) an NTLM authentication request with malformed base64-encoded data, (3) an RTSP DESCRIBE command, or (4) a DataConvertBuffer request.
Conclusion & alert: CVE-2008-5911 is rated High Risk (67.4/100): CVSS Critical severity, with high exploitation likelihood (EPSS 6.19%, 93th 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 | 2026-06-15 | 16.43% | 6.19% | -10.25% |
| 2 | 2025-03-30 | 14.31% | 16.43% | +2.13% |
| 3 | 2025-03-29 | — | 14.31% | — |
Full EPSS history (11 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 10.0 | 2.0 | HIGH |
|
10.0 | 10.0 | [email protected] |
: Per: http://docs.real.com/docs/security/SecurityUpdate121508HS.pdf Impacted Products and Versions: Helix Server Version 11.x Helix Server Version 12.x Helix Mobile Server Version 11.x Helix Mobile Server Version 12.x
: Per: http://docs.real.com/docs/security/SecurityUpdate121508HS.pdf The Fix: Version 11.1.8 and Version 12.0.1 of the Helix Server and the Helix Mobile Server have been updated to ensure that the above vulnerabilities have been resolved. SOLUTION: The vulnerability is resolved on the following platforms by installing Version 11.1.8 or Version 12.0.1 of the Helix Server and the Helix Mobile Server. This only pertains to supported versions of the platforms listed below. The updated version will be available on your RealNetworks PAM site after 11:59 p.m. PST, on December 15, 2008.
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| realnetworks | helix_server | 11.0 | cpe:2.3:a:realnetworks:helix_server:11.0:*:*:*:*:*:*:* |
| realnetworks | helix_server | 12.0.0 | cpe:2.3:a:realnetworks:helix_server:12.0.0:*:*:*:*:*:*:* |
| realnetworks | helix_server_mobile | 11.0 | cpe:2.3:a:realnetworks:helix_server_mobile:11.0:*:*:*:*:*:*:* |
| realnetworks | helix_server_mobile | 12.0.0 | cpe:2.3:a:realnetworks:helix_server_mobile:12.0.0:*:*:*:*:*:*:* |