CVE-2026-3580 in wolfSSL
Summary
by MITRE • 03/19/2026
In wolfSSL 5.8.4, constant-time masking logic in sp_256_get_entry_256_9 is optimized into conditional branches (bnez) by GCC when targeting RISC-V RV32I with -O3. This transformation breaks the side-channel resistance of ECC scalar multiplication, potentially allowing a local attacker to recover secret keys via timing analysis.
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Analysis
by VulDB Data Team • 03/24/2026
The vulnerability identified as CVE-2026-3580 affects wolfSSL version 5.8.4 and specifically targets the cryptographic implementation on RISC-V RV32I architectures. This issue represents a critical breakdown in the side-channel resistance mechanisms that are fundamental to elliptic curve cryptography implementations. The flaw manifests in the sp_256_get_entry_256_9 function where constant-time masking logic is being incorrectly optimized by the GCC compiler during aggressive optimization phases. When the compiler targets RISC-V RV32I architecture with -O3 optimization flags, it transforms the intended constant-time operations into conditional branches using bnez instructions, fundamentally compromising the cryptographic security model.
The technical implementation flaw stems from the compiler's aggressive optimization behavior that disregards the security requirements of cryptographic functions. In cryptographic contexts, particularly for elliptic curve operations, constant-time execution is essential to prevent timing attacks that could expose secret information. The sp_256_get_entry_256_9 function is part of the larger scalar multiplication process in ECC implementations where the masking logic is designed to ensure that all computational paths take equal time regardless of input values. However, the GCC optimization transforms this constant-time logic into conditional branches that execute different instruction sequences based on the input data, creating timing variations that can be measured and exploited.
This vulnerability directly impacts the operational security of systems relying on wolfSSL for cryptographic operations, particularly those implementing ECC-based security protocols such as TLS/SSL connections, digital signatures, and key exchange mechanisms. The local attacker capability means that an adversary with access to the target system can potentially perform timing analysis attacks to extract private keys used in ECC operations. The attack vector is particularly concerning because it does not require network access or external exploitation; instead, it leverages the inherent timing variations introduced by the compiler optimization to perform side-channel analysis. This represents a failure in the security-by-design principles that should govern cryptographic implementations, as the optimization that improves performance inadvertently creates a security vulnerability.
The mitigation strategies for this vulnerability involve several approaches that address both the immediate technical issue and broader security implications. The most direct solution involves disabling the problematic compiler optimizations for the affected cryptographic functions or using compiler flags that prevent the transformation of constant-time logic into conditional branches. System administrators should consider using different optimization levels or compiler settings that preserve the intended constant-time behavior of cryptographic operations. Additionally, updating to a newer version of wolfSSL that addresses this specific optimization issue or implementing custom compiler directives to enforce constant-time execution patterns would provide more robust protection. This vulnerability aligns with CWE-203, which addresses "Observable Behavior Change" in cryptographic implementations, and maps to ATT&CK technique T1059.001 for the potential exploitation through local system access. Organizations should also consider implementing additional monitoring for timing variations in cryptographic operations as part of their overall security posture to detect potential exploitation attempts.