Impact Analysis

This vulnerability primarily impacts the availability of the affected application by causing it to crash or exit unexpectedly.

An attacker with local access can exploit this flaw by providing a specially crafted regular expression that triggers a NULL pointer dereference, leading to a segmentation fault and potential denial of service.

There are no known mitigations or patches currently, and the maintainers have not responded to the issue, increasing the risk of exploitation.

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Executive Summary

[{'type': 'paragraph', 'content': "CVE-2026-3389 is a NULL Pointer Dereference vulnerability in the Squirrel programming language's standard library, specifically in the regex module within the function sqstd_rex_newnode located in sqstdlib/sqstdrex.cpp."}, {'type': 'paragraph', 'content': 'This function is responsible for allocating or initializing new nodes in the regex Abstract Syntax Tree (AST). The vulnerability occurs when the function attempts to write to a NULL pointer due to failure in verifying the validity of pointers returned during node allocation or retrieval.'}, {'type': 'paragraph', 'content': 'This typically happens when the regex complexity exceeds internal limits or when memory allocation fails, causing a segmentation fault (crash) during the compilation of a specially crafted regular expression.'}, {'type': 'paragraph', 'content': 'The attack can only be executed locally, requiring local access to the environment running Squirrel.'}] [1, 2, 3]

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability manifests as a NULL pointer dereference causing a segmentation fault (segfault) when compiling specially crafted regular expressions in the Squirrel language's regex module."}, {'type': 'paragraph', 'content': 'Detection involves reproducing the crash by running Squirrel compiled with AddressSanitizer (ASan) enabled and executing a crafted test case that triggers the fault.'}, {'type': 'paragraph', 'content': 'Suggested commands include building Squirrel with Release optimization and ASan enabled, then running the provided crashing test case:'}, {'type': 'list_item', 'content': 'Build Squirrel with ASan: `clang -fsanitize=address -O2 ...` (build instructions depend on environment)'}, {'type': 'list_item', 'content': 'Run the repro test case: `./build/bin/sq repro`'}, {'type': 'paragraph', 'content': 'Monitoring for segmentation faults or crashes in the Squirrel process when processing regex inputs can also help detect exploitation attempts.'}] [1, 3, 4]

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Mitigation Strategies

There are no known patches or countermeasures currently provided by the Squirrel project for this vulnerability.

Since the exploit requires local access and causes denial of service via application crash, immediate mitigation steps include:

• Restrict local access to systems running vulnerable versions of Squirrel up to 3.2.
• Avoid processing untrusted or maliciously crafted regular expressions in Squirrel.
• Consider replacing or upgrading the affected software if possible, or applying custom patches if available.

Monitoring for crashes and limiting user privileges can reduce the risk of exploitation.

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