yawkat LZ4 Java: LZ4BlockInputStream with stopOnEmptyBlock=false recurses once per empty block, causing StackOverflowError

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

• CVE-2026-106449: 0.42% estimated exploitation activity in the next 30 days; percentile 36.63 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When LZ4BlockInputStream is configured with stopOnEmptyBlock = false (the mode for reading concatenated block streams), it handles each empty block by calling refill() recursively. A long run of empty blocks exhausts the thread stack and throws StackOverflowError out of read() or skip(). Details In net.jpountz.lz4.LZ4BlockInputStream.refill(): Each well-formed empty block is 21 bytes and adds one stack frame, with no limit on nesting depth. In local testing, around 10,000 to 100,000 consecutive empty blocks (about 210 KB to 2.1 MB, depending on JIT state and thread stack size) threw StackOverflowError. StackOverflowError is an Error, not an IOException, so callers that only handle I/O errors for corrupt input don't catch it. Impact Applications that decode attacker-controlled LZ4Block streams with LZ4BlockInputStream.newBuilder().withStopOnEmptyBlock(false) or the deprecated LZ4BlockInputStream(InputStream, boolean) constructor can have the decoding thread fail with…

Published by the source

7 Oct 2026, 20:35 UTC

Last modified by the source

7 Oct 2026, 20:45 UTC

Source last checked

26 Oct 2026, 16:58 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-343h-94h5-c4wr

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-343h-94h5-c4wr

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# Patch Next advisory brief: CVE-2026-106449

Advisory: yawkat LZ4 Java: LZ4BlockInputStream with stopOnEmptyBlock=false recurses once per empty block, causing StackOverflowError
IDs: CVE-2026-106449, GHSA-343h-94h5-c4wr
Record: https://patchnext.com/advisories/cve-2026-106449 (revision 2, source checked 26 Oct 2026, 16:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: at.yawk.lz4:lz4-java 1.11.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven at.yawk.lz4:lz4-java: affected <= 1.11.3; fixed in 1.11.4
- Maven org.lz4:lz4-java: affected <= 1.8.1

## Suggested inspection (read-only)
- Maven at.yawk.lz4:lz4-java: check the installed version with your package manager.
- Maven org.lz4:lz4-java: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on at.yawk.lz4:lz4-java, org.lz4:lz4-java.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-343h-94h5-c4wr (OSV record GHSA-343h-94h5-c4wr lists affected ranges: Maven at.yawk.lz4:lz4-java >=0 =0 <=1.8.1)
- Verified: https://github.com/advisories/GHSA-343h-94h5-c4wr (GitHub-reviewed advisory GHSA-343h-94h5-c4wr lists affected ranges: Maven at.yawk.lz4:lz4-java >=0 =0 <=1.8.1)

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