# yawkat LZ4 Java: LZ4BlockInputStream allocates an unvalidated compressed length from the stream header

Advisory record · `GHSA-4v53-57pg-c464`

- **Identifiers:** `GHSA-4v53-57pg-c464` · `CVE-2026-106452`
- **State:** Confirmed
- **Severity:** CVSS 5.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-789](https://cwe.mitre.org/data/definitions/789.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 7 Oct 2026
- **Updated:** 7 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 7 Oct 2026, 16:17 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `at.yawk.lz4:lz4-java` (Maven): affected `<1.11.2`; fixed in `1.11.2`
- `org.lz4:lz4-java` (Maven): affected `<=1.8.1`; no fixed version yet

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> GHSA advisory: at.yawkat lz4-java before 1.11.2 has an issue where LZ4BlockInputStream allocates a compressed-input buffer sized by the compressedLen value in a legacy LZ4Block stream header before reading any payload. An attacker who can supply such a stream to an application can send a header-only input that triggers a near-2 GiB allocation and exhausts the JVM heap, causing denial of service with no valid payload needed. Upgrade to at.yawkat lz4-java 1.11.2, which rejects oversized blocks; the org.lz4 lz4-java package (1.8.1 and earlier) has no fixed version listed.

Written 2 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 5.3 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0045, the 39th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:16 UTC: First seen by agentprime
- 31 Oct 2026, 14:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-4v53-57pg-c464)

## Sources

- [GitHub Advisory Database: GHSA-4v53-57pg-c464](https://github.com/advisories/GHSA-4v53-57pg-c464)
- [OSV: GHSA-4v53-57pg-c464](https://osv.dev/vulnerability/GHSA-4v53-57pg-c464)
- <https://github.com/yawkat/lz4-java/security/advisories/GHSA-4v53-57pg-c464>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-106452>
- <https://github.com/yawkat/lz4-java/commit/bb83dd16163cdb71231af06b0a5651881148a634>
- <https://github.com/yawkat/lz4-java>
- <https://github.com/yawkat/lz4-java/releases/tag/v1.11.2>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-4v53-57pg-c464>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-4v53-57pg-c464/>. Everything for agents: <https://agentprime.io/llms.txt>.