The vulnerability identified as CVE-2026-3407 affects the YosysHQ yosys open-source synthesis tool used for hardware design. The flaw resides in the function Yosys::RTLIL::Const::set, located in the kernel/rtlil.h file, which is part of the BLIF File Parser component. This function improperly handles memory operations, leading to a heap-based buffer overflow condition. When maliciously crafted input is processed, the overflow can corrupt adjacent heap memory, potentially allowing an attacker to manipulate program behavior or cause a crash. The vulnerability is exploitable locally, requiring the attacker to have low-level privileges on the host system. No user interaction or authentication is necessary beyond local access. The issue is not reliably reproducible in all cases, which may limit exploit reliability. The vulnerability affects all yosys versions from 0.1 through 0.62, encompassing the entire release history up to the date of disclosure. While no exploits have been observed in the wild, the public availability of exploit code increases the risk of future attacks. The CVSS 4.0 vector (AV:L/AC:L/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P) reflects a medium severity rating with partial impact on availability and requiring local privileges but no user interaction or authentication. The vulnerability’s root cause is a programming error in memory management within a critical parsing function, underscoring the need for secure coding practices in hardware synthesis tools.

The primary impact of this vulnerability is on the availability and integrity of systems running vulnerable versions of yosys. Successful exploitation could lead to application crashes or potentially arbitrary code execution, depending on the heap corruption's nature and surrounding memory layout. Since yosys is widely used in hardware design and synthesis workflows, especially in academic, research, and industrial environments focused on FPGA and ASIC development, disruption could delay critical design processes or compromise the integrity of hardware designs. The local attack vector limits remote exploitation, but insider threats or compromised local accounts could leverage this flaw to escalate privileges or disrupt operations. The vulnerability does not directly affect confidentiality or remote systems but poses a risk to the stability and trustworthiness of hardware design pipelines. Organizations relying on yosys for production or research should consider the risk of downtime and potential data corruption. The lack of known exploits in the wild currently reduces immediate risk, but public exploit disclosure increases the likelihood of future attacks.

To mitigate this vulnerability, organizations should promptly update yosys to a patched version once available beyond 0.62, as the affected versions include all releases up to that point. In the absence of an official patch, users should consider applying any available community fixes or workarounds that address the heap overflow in the BLIF File Parser. Restrict local access to systems running yosys to trusted users only, minimizing the risk of exploitation by low-privilege attackers. Employ runtime protections such as heap canaries, address space layout randomization (ASLR), and memory protection mechanisms to reduce the impact of potential heap overflows. Conduct thorough input validation and sanitization on BLIF files before processing to detect malformed or malicious inputs. Implement monitoring and logging to detect abnormal crashes or behavior in yosys processes, enabling rapid incident response. Finally, integrate secure coding reviews and fuzz testing in the development lifecycle of hardware synthesis tools to prevent similar vulnerabilities.