CVE-2026-25207: Samsung Escargot Buffer Overflow Flaw

CVE-2026-25207 Overview

CVE-2026-25207 is an out-of-bounds write vulnerability in Samsung Open Source Escargot, a lightweight JavaScript engine designed for resource-constrained environments such as IoT devices. The flaw affects Escargot commit 97e8115ab1110bc502b4b5e4a0c689a71520d335 and enables attackers to overflow buffers during JavaScript execution. The weakness is classified under [CWE-787] (Out-of-bounds Write).

The vulnerability is reachable over the network with no privileges and no user interaction, making any application that embeds the affected Escargot build a viable target. Successful exploitation can compromise confidentiality, integrity, and availability of the host process.

Critical Impact

Remote attackers can trigger an out-of-bounds write in Escargot to corrupt adjacent memory, potentially leading to arbitrary code execution or denial of service in any application embedding the affected engine.

Affected Products

• Samsung Open Source Escargot JavaScript engine
• Escargot build at commit 97e8115ab1110bc502b4b5e4a0c689a71520d335
• Downstream products and IoT firmware embedding the affected Escargot revision

Discovery Timeline

• 2026-04-13 - CVE-2026-25207 published to the National Vulnerability Database
• 2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-25207

Vulnerability Analysis

Escargot is Samsung's lightweight JavaScript engine optimized for memory-constrained devices. The vulnerability is an out-of-bounds write [CWE-787], in which the engine writes data past the boundaries of an allocated buffer during script execution. Attackers craft JavaScript that drives the engine into a state where bounds checks are missing or incorrect, allowing controlled bytes to overwrite adjacent memory.

The issue is reachable through any input vector that feeds untrusted JavaScript to the embedded engine. The attack requires no authentication and no user interaction, and it executes within the privilege context of the host application. Depending on the surrounding heap layout, the write can corrupt object metadata, function pointers, or control structures.

Root Cause

The root cause is missing or insufficient validation on write boundaries within an internal buffer manipulation path in the engine. Memory-corruption flaws of this class typically arise from off-by-one errors, incorrect length calculations, or trust placed in attacker-controlled size fields. The maintainers addressed the defect in the upstream fix tracked by Samsung Escargot Pull Request #1554.

Attack Vector

An attacker delivers crafted JavaScript to an application that embeds the vulnerable Escargot build. Examples include IoT firmware that processes scripts received over a network protocol, hybrid mobile applications, or smart-device control planes that evaluate remote configuration scripts. Once the malicious script executes, the out-of-bounds write corrupts memory and can be chained with heap-grooming techniques to redirect control flow.

No public proof-of-concept exploit is currently listed for CVE-2026-25207, and the vulnerability is not present on the CISA Known Exploited Vulnerabilities catalog. The defect is described in prose only; refer to the upstream pull request for the corrective code changes.

Detection Methods for CVE-2026-25207

Indicators of Compromise

• Unexpected crashes, segmentation faults, or abort signals from processes that embed the Escargot engine
• JavaScript payloads delivered to IoT or embedded endpoints that contain unusually large typed arrays, string buffers, or recursive object constructions
• Anomalous outbound connections originating from device processes immediately after script ingestion

Detection Strategies

• Inventory all firmware, mobile apps, and embedded products that bundle Escargot and compare bundled commit hashes against 97e8115ab1110bc502b4b5e4a0c689a71520d335
• Enable Address Sanitizer or equivalent runtime memory checkers in development and QA builds to surface out-of-bounds writes during testing
• Inspect ingress channels that deliver JavaScript to embedded devices for malformed or oversized script payloads

Monitoring Recommendations

• Forward process crash telemetry and core dumps from affected devices to a centralized analytics pipeline for triage
• Monitor network traffic to IoT and embedded fleets for unauthenticated script delivery or unusual command-and-control patterns
• Track new commits and releases on the upstream Samsung Escargot repository to confirm patch adoption

How to Mitigate CVE-2026-25207

Immediate Actions Required

• Identify every product, firmware image, and application that links against Escargot at or near commit 97e8115ab1110bc502b4b5e4a0c689a71520d335
• Rebuild affected software against a patched Escargot revision that incorporates the fix from Samsung Escargot Pull Request #1554
• Restrict untrusted JavaScript input paths to embedded devices until patched builds are deployed

Patch Information

The upstream fix is tracked in Samsung Escargot Pull Request #1554. Vendors that ship Escargot as a dependency should integrate the patched commit, rebuild downstream artifacts, and distribute updated firmware or application packages. Devices that cannot receive over-the-air updates should be scheduled for manual upgrade.

Workarounds

• Block or filter untrusted JavaScript at the network or application boundary before it reaches the Escargot interpreter
• Run the embedding application under tighter sandboxing, seccomp policies, or reduced privileges to limit the impact of memory corruption
• Disable optional features that evaluate remote scripts where they are not strictly required for device operation

# Verify the Escargot commit currently built into a project
cd /path/to/escargot
git rev-parse HEAD

# If the output matches the vulnerable commit, update and rebuild
git fetch origin
git checkout main
git pull origin main
# Confirm PR #1554 is merged into the checked-out tree before rebuilding