VulnerabilityPublished 2 Mar 2026

CVE-2026-3407: YosysHQ yosys · Heap-based Buffer Overflow

Affects YosysHQ yosysSource CVE Database V5

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Public exploit available · CVSS 4.8 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Local
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 2 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
YosysHQyosys	Affected 0.1 – 0.62 62 affected builds	Fixed in–
GitHubyosyshq/yosys`pkg:github/yosyshq/yosys`Other threats	Affected 0.1 – 0.62 62 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

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.

Description

A vulnerability was determined in YosysHQ yosys up to 0.62. This affects the function Yosys::RTLIL::Const::set of the file kernel/rtlil.h of the component BLIF File Parser. This manipulation causes heap-based buffer overflow. It is possible to launch the attack on the local host. The exploit has been publicly disclosed and may be utilized. Applying a patch is the recommended action to fix this issue. It appears that the issue is not reproducible all the time.

Impact

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.

References

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