CVE-2026-58303: Stack Buffer Overflow in Samsung Escargot JavaScript Engine

Technical summary

CVE-2026-58303 is a stack-based buffer overflow (CWE-121) in Samsung's Escargot JavaScript engine. The flaw exists in versions prior to commit b30b63fc63b403907d8137da1c65aaa4521fe74e. An attacker can craft input that, when processed by the JavaScript engine, overflows a stack buffer, corrupting memory and potentially executing arbitrary code on the affected system. The vulnerability requires user interaction to trigger and is limited to the local attack surface, meaning the attacker must already have the ability to run code or provide input that the vulnerable application will process.

Business impact

Organizations using Escargot—either directly or as part of embedded systems, IoT devices, or Samsung products—face potential service interruptions due to crashes. More critically, if an attacker gains the ability to execute code through this vulnerability, they could compromise the confidentiality and integrity of data processed by those systems. Devices running vulnerable versions are at risk if they parse untrusted JavaScript input. This is particularly relevant for embedded and mobile deployments where Escargot may be the primary or sole JavaScript runtime.

Affected systems

The vulnerability affects Samsung Open Source Escargot prior to commit b30b63fc63b403907d8137da1c65aaa4521fe74e. No specific vendor products are listed in the known affected database, suggesting this primarily impacts direct users of the Escargot engine or downstream consumers who have integrated it. Verify the specific version and build date of your Escargot installation against the patched commit hash provided by Samsung to determine exposure.

Exploitability

Exploitation requires user interaction (UI:R in the CVSS vector), meaning an attacker must trick a user into opening a file, clicking a link, or otherwise providing input to a vulnerable Escargot instance. No known public exploit code has been added to the Known Exploited Vulnerabilities catalog, and there is no evidence of active exploitation in the wild. However, the technical barrier to exploitation is moderate—a skilled attacker with JavaScript knowledge can likely craft a proof-of-concept. Once weaponized, the attack is reliable against vulnerable builds.

Remediation

Apply the fix by upgrading to a version of Escargot that includes commit b30b63fc63b403907d8137da1c65aaa4521fe74e or later. If you are using Escargot as a library or engine within a larger application, coordinate with your vendor to obtain a patched release. If you maintain a custom build, pull the latest source from Samsung's repository and rebuild. Until patching is complete, restrict the execution of untrusted JavaScript code and educate users not to open suspicious files in applications that use Escargot.

Patch guidance

Identify all systems and applications in your environment that depend on Escargot, including embedded systems and IoT devices. Check Samsung's official Escargot repository for the patched commit. Most users will need to rebuild or obtain a new binary release from their vendor. Test the patched version in a non-production environment first, as JavaScript engine updates can occasionally break compatibility. Given the MEDIUM severity and the requirement for user interaction, schedule patching within your standard maintenance windows, but prioritize systems that process untrusted JavaScript input.

Detection guidance

Monitor for crashes or unexpected termination of applications that use Escargot, particularly when processing user-supplied input or downloaded files. Implement logging at the JavaScript engine level if possible, or review system logs for segmentation faults and access violations in processes known to use Escargot. Network-based detection is limited because the attack surface is local; focus on endpoint detection rules that flag abnormal process behavior following file opens or downloads. If your organization has a Software Bill of Materials (SBOM) practice, scan for Escargot versions and cross-reference against the vulnerable commit hash.

Why prioritize this

Although the CVSS score is MEDIUM (6.1), this vulnerability warrants prompt attention because stack-based buffer overflows, even with user interaction requirements, can lead to code execution. The impact on availability is high, and integrity compromise is possible. Escargot's use in embedded and mobile systems means patching may be more complex than typical application updates. Organizations that rely on Escargot for processing untrusted content should prioritize this patch. Conversely, if Escargot is only used in tightly controlled environments with trusted input, remediation can be scheduled with lower urgency.

Risk score, explained

The CVSS 3.1 score of 6.1 reflects a MEDIUM-severity issue: local attack vector (AV:L) means the attacker needs local presence or ability to provide input; low complexity (AC:L) indicates the exploit is straightforward to reproduce; no privilege escalation is required (PR:N); user interaction is necessary (UI:R), reducing real-world exploitability; scope is unchanged (S:U), limiting blast radius; no confidentiality impact (C:N); integrity can be compromised (I:L); and availability is significantly impacted (A:H). The high availability impact reflects the likelihood of application crash. The overall MEDIUM rating appropriately positions this as important but not critical.

Frequently asked questions