CVE-2006-5201 in JRE
Summary
by MITRE
Multiple packages on Sun Solaris, including (1) NSS; (2) Java JDK and JRE 5.0 Update 8 and earlier, SDK and JRE 1.4.x up to 1.4.2_12, and SDK and JRE 1.3.x up to 1.3.1_19; (3) JSSE 1.0.3_03 and earlier; (4) IPSec/IKE; (5) Secure Global Desktop; and (6) StarOffice, when using an RSA key with exponent 3, removes PKCS-1 padding before generating a hash, which allows remote attackers to forge a PKCS #1 v1.5 signature that is signed by that RSA key and prevents these products from correctly verifying X.509 and other certificates that use PKCS #1.
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Analysis
by VulDB Data Team • 04/23/2026
This vulnerability represents a critical cryptographic flaw affecting multiple Sun Microsystems products running on Solaris operating systems. The issue stems from improper implementation of RSA signature verification processes where the affected software removes PKCS-1 padding before generating a hash, creating a fundamental weakness in the digital signature validation mechanism. This flaw specifically impacts RSA keys with exponent 3, which are commonly used in various security protocols and certificate systems. The vulnerability affects a wide range of products including Network Security Services, Java Development Kits and Runtime Environments across multiple versions, Java Secure Socket Extension components, IPSec/IKE implementations, Secure Global Desktop solutions, and StarOffice applications. The technical nature of this flaw aligns with CWE-327, which addresses the use of weak or broken cryptographic algorithms, and CWE-328, which covers the use of weak hash functions. From an operational perspective, this vulnerability creates a significant risk for authentication and certificate validation processes, as it allows remote attackers to forge PKCS #1 v1.5 signatures that would appear valid to the affected systems. This capability undermines the integrity of X.509 certificates and other cryptographic certificates that rely on PKCS #1 v1.5 signature schemes, potentially enabling man-in-the-middle attacks, unauthorized system access, and certificate spoofing. The vulnerability operates at the application layer and can be exploited through network-based attacks without requiring authentication, making it particularly dangerous in enterprise environments where these products are commonly deployed. Attackers could leverage this flaw to bypass authentication mechanisms, impersonate legitimate systems, or compromise certificate-based security controls that depend on proper RSA signature verification. The impact extends beyond individual product failures to potentially compromise entire security infrastructures that rely on the integrity of RSA-signed certificates and digital signatures. Organizations using these affected products face significant risks including unauthorized access to sensitive systems, data breaches, and complete bypass of security controls that depend on certificate validation. The vulnerability is particularly concerning because it affects multiple versions of widely-used software components, including Java runtime environments that are integral to enterprise applications and web services. This flaw demonstrates a critical failure in cryptographic implementation that violates fundamental security principles outlined in the NIST Special Publication 800-57 and other cryptographic standards. The attack surface is extensive given the widespread deployment of affected Java versions and security components across enterprise networks, making this vulnerability a high-priority target for exploitation. Organizations should immediately implement mitigations including updating to patched versions of affected software, disabling vulnerable RSA key usage where possible, and implementing additional verification mechanisms to detect forged signatures. The vulnerability also highlights the importance of proper cryptographic implementation practices and adherence to established security standards such as those defined in the ATT&CK framework for credential access and defense evasion techniques. System administrators should conduct thorough inventory assessments to identify all affected systems and ensure comprehensive patch deployment across all vulnerable products. The remediation process requires careful consideration of compatibility issues and potential disruptions to existing applications that may depend on the vulnerable cryptographic implementations.