CVE-2023-43642: Missing upper bound check on chunk length in snappy-java

First published: Mon Sep 25 2023(Updated: )

### Summary snappy-java is a data compression library in Java. Its SnappyInputStream was found to be vulnerable to Denial of Service (DoS) attacks when decompressing data with a too-large chunk size. Due to missing upper bound check on chunk length, an unrecoverable fatal error can occur. ### Scope All versions of snappy-java including the latest released version 1.1.10.3. A fix is applied in 1.1.10.4 ### Details While performing mitigation efforts related to [CVE-2023-34455](https://nvd.nist.gov/vuln/detail/CVE-2023-34455) in Confluent products, our Application Security team closely analyzed the fix that was accepted and merged into snappy-java version 1.1.10.1 in [this](https://github.com/xerial/snappy-java/commit/3bf67857fcf70d9eea56eed4af7c925671e8eaea) commit. The check on [line 421](https://github.com/xerial/snappy-java/commit/3bf67857fcf70d9eea56eed4af7c925671e8eaea#diff-c3e53610267092989965e8c7dd2d4417d355ff7f560f9e8075b365f32569079fR421) only attempts to check if chunkSize is not a negative value. We believe that this is an inadequate fix as it misses an upper-bounds check for overly positive values such as 0x7FFFFFFF (or (2,147,483,647 in decimal) before actually [attempting to allocate](https://github.com/xerial/snappy-java/commit/3bf67857fcf70d9eea56eed4af7c925671e8eaea#diff-c3e53610267092989965e8c7dd2d4417d355ff7f560f9e8075b365f32569079fR429) the provided unverified number of bytes via the “chunkSize” variable. This missing upper-bounds check can lead to the applications depending upon snappy-java to allocate an inappropriate number of bytes on the heap which can then cause an java.lang.OutOfMemoryError exception. Under some specific conditions and contexts, this can lead to a Denial-of-Service (DoS) attack with a direct impact on the availability of the dependent implementations based on the usage of the snappy-java library for compression/decompression needs. ### PoC Compile and run the following code: ``` package org.example; import org.xerial.snappy.SnappyInputStream; import java.io.*; public class Main { public static void main(String[] args) throws IOException { byte[] data = {-126, 'S', 'N', 'A', 'P', 'P', 'Y', 0, 0, 0, 0, 0, 0, 0, 0, 0,(byte) 0x7f, (byte) 0xff, (byte) 0xff, (byte) 0xff}; SnappyInputStream in = new SnappyInputStream(new ByteArrayInputStream(data)); byte[] out = new byte[50]; try { in.read(out); } catch (Exception ignored) { } } } ``` ### Impact Denial of Service of applications dependent on snappy-java especially if `ExitOnOutOfMemoryError` or `CrashOnOutOfMemoryError` is configured on the JVM. ### Credits Jan Werner, Mukul Khullar and Bharadwaj Machiraju from Confluent's Application Security team. We kindly request for a new CVE ID to be assigned once you acknowledge this vulnerability.

Credit: security-advisories@github.com security-advisories@github.com security-advisories@github.com

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