CVE-2026-58306 Overview
CVE-2026-58306 is a heap-based buffer overflow vulnerability [CWE-122] in Samsung Open Source Escargot, a lightweight JavaScript engine designed for resource-constrained devices. The flaw affects all versions of Escargot before commit ef525f337fafddecde77a3c426212a84bb20cb98.
An attacker exploits the vulnerability by convincing a local user to process a crafted JavaScript input. Successful exploitation corrupts heap memory, causing integrity loss and application termination. The issue carries a CVSS 3.1 score of 6.1 with vector AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H.
Critical Impact
Local attackers can trigger heap corruption in the Escargot JavaScript engine through crafted script input, resulting in memory integrity loss and denial of service on embedded and IoT devices that embed the runtime.
Affected Products
- Samsung Open Source Escargot JavaScript engine
- All Escargot builds prior to commit ef525f337fafddecde77a3c426212a84bb20cb98
- Embedded applications and IoT firmware that link the vulnerable Escargot runtime
Discovery Timeline
- 2026-07-09 - CVE-2026-58306 published to the National Vulnerability Database
- 2026-07-09 - Last updated in NVD database
Technical Details for CVE-2026-58306
Vulnerability Analysis
Escargot is a lightweight JavaScript engine that Samsung maintains for embedded and IoT workloads. The engine parses and executes untrusted script content, so memory safety inside its allocators directly determines runtime integrity.
CVE-2026-58306 is a heap-based buffer overflow that occurs while Escargot processes attacker-controlled input. Writing past the bounds of a heap allocation corrupts adjacent metadata and object structures managed by the engine. The result is loss of integrity within the process and, in most reachable code paths, an abort of the JavaScript host.
The vulnerability requires local access and user interaction, which aligns with scenarios where a user opens or evaluates a malicious script inside an application that embeds Escargot. Confidentiality is not impacted according to the published CVSS vector, but availability impact is high.
Root Cause
The root cause is an out-of-bounds write on the heap during script processing inside Escargot. Upstream maintainers corrected the defect in commit ef525f337fafddecde77a3c426212a84bb20cb98, delivered through GitHub Pull Request #1584. The corresponding defect report is tracked in GitHub Issue #1576.
Attack Vector
An attacker crafts a malicious JavaScript payload and delivers it to a local user running an application built on a vulnerable Escargot version. When the victim executes the payload, Escargot writes beyond an allocated heap buffer during processing. The engine state becomes corrupted, and the host application terminates or behaves unpredictably. No network access and no elevated privileges are required.
No public proof-of-concept exploit is available at the time of publication. Refer to the upstream issue tracker for technical reproduction details.
Detection Methods for CVE-2026-58306
Indicators of Compromise
- Unexpected crashes or abnormal termination of applications embedding the Escargot JavaScript engine
- Heap corruption signatures such as glibc malloc() assertions, AddressSanitizer reports, or SIGABRT events tied to Escargot processes
- Execution of untrusted or unexpected JavaScript files staged in user-writable directories before a crash
Detection Strategies
- Inventory software and firmware images to identify components linking Escargot below commit ef525f337fafddecde77a3c426212a84bb20cb98.
- Enable heap protections such as AddressSanitizer or hardened allocators in development and QA builds to surface the overflow deterministically.
- Correlate process crash telemetry with recent script file drops or downloads on the affected host.
Monitoring Recommendations
- Forward host crash reports and core dumps from IoT and embedded devices to a central log platform for review.
- Alert on repeated abnormal exits of applications that host Escargot, which can indicate exploitation attempts.
- Track file creation events for .js files in user-writable paths that immediately precede application faults.
How to Mitigate CVE-2026-58306
Immediate Actions Required
- Rebuild or update Escargot to a version that includes commit ef525f337fafddecde77a3c426212a84bb20cb98 or later.
- Redistribute patched firmware and application binaries to all downstream devices and endpoints embedding Escargot.
- Restrict execution of untrusted JavaScript inside applications hosting the engine until patches are deployed.
Patch Information
Samsung resolved the heap-based buffer overflow in upstream commit ef525f337fafddecde77a3c426212a84bb20cb98, merged through Escargot Pull Request #1584. Consumers of Escargot must recompile against the fixed source tree and republish affected products. Additional context is available in Escargot Issue #1576.
Workarounds
- Disable or gate JavaScript evaluation features in applications that expose Escargot to user-supplied input.
- Apply operating system exploit mitigations such as ASLR and heap hardening to reduce reliability of memory corruption exploitation.
- Enforce least-privilege execution for processes that embed Escargot to contain the impact of a successful crash or corruption.
# Rebuild Escargot from the patched upstream source
git clone https://github.com/Samsung/escargot.git
cd escargot
git checkout ef525f337fafddecde77a3c426212a84bb20cb98
cmake -H. -Bout/release -DESCARGOT_HOST=linux -DESCARGOT_ARCH=x64 -DESCARGOT_MODE=release
cmake --build out/release
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
