CVE-2026-47309: Samsung Escargot Recursion Vulnerability

CVE-2026-47309 Overview

CVE-2026-47309 is an uncontrolled recursion vulnerability in Samsung Open Source Escargot, a lightweight JavaScript engine designed for resource-constrained devices. The flaw allows oversized serialized data payloads to trigger unbounded recursive processing, exhausting stack memory and crashing the host process. The issue affects Escargot at commit 590345cc6258317c5da850d846ce6baaf2afc2d3. The vulnerability is categorized under [CWE-674: Uncontrolled Recursion] and requires local access with user interaction to exploit.

Critical Impact

A local attacker can deliver a crafted serialized payload to Escargot and force a denial of service through stack exhaustion, terminating any application embedding the engine.

Affected Products

• Samsung Open Source Escargot JavaScript engine
• Escargot commit 590345cc6258317c5da850d846ce6baaf2afc2d3
• Applications and embedded devices that bundle the affected Escargot build

Discovery Timeline

• 2026-05-19 - CVE-2026-47309 published to NVD
• 2026-05-19 - Last updated in NVD database

Technical Details for CVE-2026-47309

Vulnerability Analysis

Escargot is Samsung's open source JavaScript engine optimized for IoT and embedded environments. The engine exposes serialization and deserialization routines used to reconstruct JavaScript values and object graphs from byte streams. CVE-2026-47309 stems from the absence of depth limits when parsing nested structures in serialized data.

When the engine encounters a deeply nested or oversized serialized payload, the parser invokes itself recursively for each nested element. Without a bound on recursion depth or input size, the call stack grows until it overflows. The result is an abnormal process termination rather than memory corruption.

The impact is confined to availability. The CVSS vector indicates no confidentiality or integrity impact, consistent with a stack-exhaustion denial of service. The EPSS probability of 0.004% reflects the local attack vector and the limited utility of the bug for remote attackers.

Root Cause

The root cause is unbounded recursion in Escargot's serialized data handling path. The deserialization logic descends into each nested object or array without enforcing a maximum depth or validating overall payload size before traversal. [CWE-674] applies directly: a recursive call chain whose depth is controlled by attacker-supplied input.

Attack Vector

Exploitation requires local access and user interaction, such as opening a file or loading content into an application that embeds Escargot. The attacker crafts a serialized payload containing deeply nested structures and delivers it to the target. When the victim's application deserializes the payload, the engine recurses until the stack is exhausted and the host process aborts.

No authenticated network path or privilege escalation is involved. The proposed fix is tracked in the GitHub Pull Request for Escargot, which introduces guards against oversized serialized data payloads.

Detection Methods for CVE-2026-47309

Indicators of Compromise

• Repeated crashes or segmentation faults in processes that link against libescargot when handling external JavaScript or serialized input.
• Core dumps showing deep recursive call chains inside Escargot deserialization functions.
• Application logs reporting stack overflow conditions tied to JavaScript content loading.

Detection Strategies

• Scan source trees and build artifacts for Escargot commit 590345cc6258317c5da850d846ce6baaf2afc2d3 or earlier and flag unpatched builds.
• Inspect serialized JavaScript inputs for abnormal nesting depth or file sizes that exceed application norms.
• Instrument deserialization entry points with depth counters during fuzzing or QA to detect runaway recursion before deployment.

Monitoring Recommendations

• Alert on crash telemetry from applications and IoT firmware that embed Escargot, particularly repeated faults from the same input source.
• Monitor file delivery channels, such as email attachments and removable media, for serialized JavaScript payloads with anomalous structure.
• Track upstream Escargot releases and integrate commit-level software composition analysis into CI pipelines.

How to Mitigate CVE-2026-47309

Immediate Actions Required

• Update Escargot to a build that includes the fix from Escargot PR #1565 once merged and released.
• Rebuild and redeploy all downstream applications and firmware images that statically link the affected Escargot commit.
• Restrict the sources from which embedded applications accept serialized JavaScript data to trusted origins only.

Patch Information

The upstream fix is proposed in the GitHub Pull Request for Escargot. The change adds validation against oversized serialized payloads in the deserialization path. Vendors shipping products that embed Escargot should rebase onto the patched commit and rebuild affected components.

Workarounds

• Validate serialized JavaScript inputs at the application layer and reject payloads above a conservative size threshold before passing them to Escargot.
• Run Escargot-hosting processes under resource limits, such as ulimit -s, so a crash does not affect other services on the device.
• Disable or gate features that deserialize untrusted JavaScript content until the patched engine is deployed.

# Configuration example: cap stack size and reject oversized payloads
ulimit -s 2048
find /opt/app/data -name '*.bin' -size +256k -delete