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https://issues.apache.org/jira/browse/COMPRESS-713?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gary D. Gregory resolved COMPRESS-713.
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Fix Version/s: 1.29.0
Resolution: Fixed
Hello [~pbebr],
A fix is now in git master and snapshot builds in
https://repository.apache.org/content/repositories/snapshots/
Please verify your use case and let us know.
> Unchecked pre-decremental notation in for-loop as array index causes
> ArrayOutOfBounds access
> --------------------------------------------------------------------------------------------
>
> Key: COMPRESS-713
> URL: https://issues.apache.org/jira/browse/COMPRESS-713
> Project: Commons Compress
> Issue Type: Bug
> Components: Compressors
> Environment: Ubuntu 24.04
> $ java --version
> openjdk 21.0.8 2025-07-15
> OpenJDK Runtime Environment (build 21.0.8+9-Ubuntu-0ubuntu124.04.1)
> OpenJDK 64-Bit Server VM (build 21.0.8+9-Ubuntu-0ubuntu124.04.1, mixed mode,
> sharing)
> Reporter: Philip Betzler-Braun
> Assignee: Gary D. Gregory
> Priority: Major
> Fix For: 1.29.0
>
> Attachments: ArrayOutOfBoundsZipInArchiveInputStreamReproducer.java
>
>
> *Issue:*
> LZWInputStream
> (org.apache.commons.compress.compressors.lzw.LZWInputStream.expandCodeToOutputStack(LZWInputStream.java:150))
> contains a byte array outputStack with the size 8192 and an int
> outputStackLocation that is used to find the position to write to in the
> stack. In the function expandCodeToOutputStack (LZWInputStream.java:150)
> there is a C-style pre-decremental statement that is executed in a for-loop
> and never checks what it's value is and if the loop goes on for more then
> 8192 iterations, it causes an ArrayOutOfBounds access to the outputStack byte
> array.
>
> Begin: LZWInputStream.java:149
> {code:java}
> for (int entry = code; entry >= 0; entry = prefixes[entry]) {
> outputStack[--outputStackLocation] = characters[entry];
> } {code}
>
> *Suggestion:*
> * Catch the ArrayOutOfBounds exception and throw a library specific
> exception.
>
> *Reproduction:*
> (reprocuder in attached file -> intended location is:
> src/test/java/org/apache/commons/compress/archivers/zip/ArrayOutOfBoundsZipInArchiveInputStreamReproducer.java)
> [^ArrayOutOfBoundsZipInArchiveInputStreamReproducer.java]
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