CVE-2026-0822: QuickJS Buffer Overflow Vulnerability

CVE-2026-0822 Overview

A heap-based buffer overflow vulnerability has been identified in quickjs-ng QuickJS versions up to 0.11.0. This memory corruption flaw affects the js_typed_array_sort function within the quickjs.c file. The vulnerability arises from improper memory boundary handling during the manipulation of typed arrays, potentially leading to memory corruption.

Critical Impact

Remote attackers can exploit this heap-based buffer overflow to potentially corrupt memory, cause denial of service, or achieve code execution through specially crafted JavaScript input processed by the vulnerable QuickJS engine.

Affected Products

• quickjs-ng QuickJS versions up to 0.11.0

Discovery Timeline

• January 10, 2026 - CVE-2026-0822 published to NVD
• January 13, 2026 - Last updated in NVD database

Technical Details for CVE-2026-0822

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the js_typed_array_sort function, which is responsible for sorting typed arrays in the QuickJS JavaScript engine. When processing certain input, the function fails to properly validate memory boundaries, leading to heap-based buffer overflow conditions.

QuickJS is a lightweight JavaScript engine designed for embedding in applications. The js_typed_array_sort function handles sorting operations on TypedArray objects (such as Int32Array, Float64Array, etc.). During the sort operation, improper bounds checking allows memory writes beyond allocated buffer boundaries, corrupting heap memory structures.

The vulnerability can be triggered remotely when a victim application using the vulnerable QuickJS library processes attacker-controlled JavaScript code. An exploit is publicly available, increasing the risk of active exploitation in the wild.

Root Cause

The root cause stems from insufficient bounds validation in the js_typed_array_sort function within quickjs.c. When sorting typed array elements, the function does not adequately verify that memory access operations remain within the allocated buffer boundaries. This oversight allows heap memory corruption when processing maliciously crafted typed arrays with specific element configurations designed to trigger out-of-bounds write operations.

Attack Vector

The attack vector is network-based, allowing remote exploitation. An attacker can exploit this vulnerability by:

1. Crafting malicious JavaScript code containing a specially constructed typed array
2. Triggering the sort operation on the typed array to invoke the vulnerable js_typed_array_sort function
3. Exploiting the heap-based buffer overflow to corrupt adjacent memory structures

The vulnerability requires user interaction, as the victim must process the attacker-supplied JavaScript code through an application embedding the vulnerable QuickJS engine. Successful exploitation could result in memory corruption, denial of service, or potentially arbitrary code execution depending on heap layout and exploitation techniques employed.

Technical details and proof-of-concept information can be found in GitHub Issue #1297.

Detection Methods for CVE-2026-0822

Indicators of Compromise

• Unexpected crashes or segmentation faults in applications using QuickJS when processing JavaScript code
• Abnormal memory allocation patterns or heap corruption signatures in QuickJS process memory
• JavaScript files containing unusual typed array operations followed by sort method calls

Detection Strategies

• Monitor QuickJS-embedded applications for crash patterns indicating heap corruption
• Implement memory sanitizers (ASAN/MSAN) in development and testing environments to detect buffer overflow conditions
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation attempts

Monitoring Recommendations

• Enable application crash logging and analyze stack traces for js_typed_array_sort function involvement
• Monitor for unusual JavaScript payloads targeting typed array sort operations
• Implement runtime application self-protection (RASP) to detect heap-based buffer overflow exploitation attempts

How to Mitigate CVE-2026-0822

Immediate Actions Required

• Update quickjs-ng QuickJS to a version that includes commit 53eefbcd695165a3bd8c584813b472cb4a69fbf5 or later
• Review applications embedding QuickJS and prioritize patching for internet-facing services
• Implement input validation for JavaScript code processed by QuickJS where possible

Patch Information

The vulnerability has been addressed in the quickjs-ng repository. The fix is available through:

• Patch Commit: 53eefbcd695165a3bd8c584813b472cb4a69fbf5
• Pull Request: PR #1298

Organizations using quickjs-ng QuickJS should apply the patch immediately by updating to a version containing the security fix.

Workarounds

• Restrict JavaScript execution to trusted sources only until patching is complete
• Implement sandboxing for QuickJS engine execution to limit impact of potential exploitation
• Consider disabling typed array sort operations if not required by application functionality