CVE-2026-42996: JS8Call · Stack-based Buffer Overflow

Attack Vector: Network

The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

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: None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

User Interaction: None

The vulnerable system can be exploited without interaction from any human user, other than the attacker.

Vulnerable system confidentiality: High

There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Vulnerable system integrity: High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the vulnerable system. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the vulnerable system.

Vulnerable system availability: High

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Subsequent system confidentiality: High

There is a total loss of confidentiality, resulting in all resources within the Subsequent System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Subsequent system integrity: High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Subsequent System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Subsequent System.

Subsequent system availability: High

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Subsequent System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Subsequent System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Safety: Present

Consequences of the vulnerability meet definition of IEC 61508 consequence categories of "marginal," "critical," or "catastrophic."

Automatable: Yes

Attackers can reliably automate all 4 steps of the kill chain. These steps are reconnaissance, weaponization, delivery, and exploitation (e.g., the vulnerability is “wormable”).

Recovery: User

The system requires manual intervention by the user to recover services, after an attack has been performed.

Value Density: Diffuse

The vulnerable system has limited resources. That is, the resources that the attacker will gain control over with a single exploitation event are relatively small. An example of Diffuse (think: limited) Value Density would be an attack on a single email client vulnerability.

Vulnerability Response Effort: Moderate

The actions required to respond to a vulnerability require some effort on behalf of the consumer and could cause minimal service impact to implement. Examples include: simple remote update, disabling of a subsystem, or a low-touch software upgrade such as a driver update.

Provider Urgency: Green

Provider has assessed the impact of this vulnerability as having a reduced urgency.

Definitions: FIRST CVSS v4.0 specification.