CVE-2026-92259 Overview
CVE-2026-92259 is an integer overflow vulnerability [CWE-190] in Samsung's Escargot JavaScript engine. The flaw exists in the bytecode-cache handling logic and allows a local attacker with write access to the bytecode-cache directory to trigger a heap-based buffer overflow. Successful exploitation results in denial of service. The issue affects Escargot commit ac94df78493ee6fede286620d94f724e46b4d238 and is tracked upstream in Samsung Escargot Pull Request #1650.
Critical Impact
A local attacker with write privileges to the bytecode-cache directory can craft a malicious cache file that induces integer overflow and heap corruption, crashing the Escargot runtime and any application embedding it.
Affected Products
- Samsung Escargot JavaScript engine at commit ac94df78493ee6fede286620d94f724e46b4d238
- Applications and embedded devices bundling the affected Escargot build
- Downstream projects consuming Escargot's bytecode caching subsystem
Discovery Timeline
- 2026-09-15 - CVE-2026-92259 published to the National Vulnerability Database (NVD)
- 2026-09-16 - Last updated in the NVD database
Technical Details for CVE-2026-92259
Vulnerability Analysis
Escargot is Samsung's lightweight JavaScript engine designed for resource-constrained environments. To accelerate script loading, Escargot serializes compiled bytecode to a cache directory and reloads it on subsequent executions. The deserialization path trusts size fields embedded in the cache file when computing allocation sizes for on-heap structures.
An attacker who can write to the bytecode-cache directory can craft a cache file whose size fields, when combined arithmetically, wrap around the integer bounds. The wrapped value is then used to allocate an undersized heap buffer, while subsequent copy operations write the original, unwrapped length worth of bytes. This produces a heap-based buffer overflow that corrupts adjacent heap metadata and causes the engine to abort.
Root Cause
The defect is a classic integer overflow or wraparound [CWE-190] in cache-file parsing. Length and count fields read from the untrusted cache are used in multiplication or addition without validating that the result fits within the target integer type. The upstream fix in Escargot Pull Request #1650 introduces bounds checks on the arithmetic used to size cache-derived allocations.
Attack Vector
Exploitation requires local access with write permission to the directory where Escargot stores cached bytecode. The attacker replaces or plants a crafted cache file. When the target application starts and Escargot loads the poisoned cache, the parser triggers the integer overflow and the resulting heap overflow crashes the process. The vulnerability does not grant confidentiality or integrity impact; the effect is limited to availability.
No public proof-of-concept is available and no in-the-wild exploitation has been reported. See the upstream patch discussion for technical details on the vulnerable arithmetic.
Detection Methods for CVE-2026-92259
Indicators of Compromise
- Unexpected write activity from non-privileged users or processes into Escargot's bytecode-cache directory
- Repeated crashes or abort signals originating from processes that embed the Escargot runtime
- Cache files whose declared internal size fields do not match the on-disk file length
- New or modified .cache artifacts in Escargot working directories outside of application update windows
Detection Strategies
- Enable filesystem auditing on the Escargot bytecode-cache directory and alert on writes from unexpected principals
- Correlate application crash telemetry with recent modifications to cache files on the same host
- Track the deployed Escargot commit hash across build artifacts and flag hosts still running ac94df78493ee6fede286620d94f724e46b4d238
- Validate cache file integrity at application startup using signed hashes generated during the build pipeline
Monitoring Recommendations
- Monitor process crash rates for applications embedding Escargot and investigate spikes
- Track directory access control changes on cache paths to detect permission drift
- Ingest host filesystem and process telemetry into a central data lake for cross-host correlation
- Alert on integer-overflow style crash signatures such as SIGABRT from allocator instrumentation
How to Mitigate CVE-2026-92259
Immediate Actions Required
- Inventory all applications and firmware images that embed Escargot and identify those built from commit ac94df78493ee6fede286620d94f724e46b4d238
- Restrict write permissions on the bytecode-cache directory to the account that owns the Escargot process
- Delete existing cache files and force regeneration under hardened permissions
- Rebuild affected products with the patched Escargot revision from upstream
Patch Information
The fix is merged in Samsung Escargot Pull Request #1650, which adds arithmetic bounds validation to the bytecode cache loader. Downstream consumers must pull a revision that includes this commit and rebuild dependent binaries. No vendor-specific advisory URL is currently published beyond the upstream repository.
Workarounds
- Disable Escargot's bytecode cache where the runtime supports it, forcing scripts to be recompiled on each execution
- Store the cache directory on a filesystem that only the Escargot service account can write to
- Apply mandatory access controls such as SELinux or AppArmor profiles to constrain writes to the cache path
- Validate cache files against a known-good hash before allowing the engine to load them
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
