CVE-2026-32829

High

Description

lz4_flex is a pure Rust implementation of LZ4 compression/decompression. In versions 0.11.5 and below, and 0.12.0, decompressing invalid LZ4 data can leak sensitive information from uninitialized memory or from previous decompression operations. The library fails to properly validate offset values during LZ4 "match copy operations," allowing out-of-bounds reads from the output buffer. The block-based API functions (`decompress_into`, `decompress_into_with_dict`, and others when `safe-decode` is disabled) are affected, while all frame APIs are unaffected. The impact is potential exposure of sensitive data and secrets through crafted or malformed LZ4 input. This issue has been fixed in versions 0.11.6 and 0.12.1.

SeverityHigh
CVSS7.5
Exploit probability—
ProductPseitz Lz4 Flex
PublishedMar 20, 2026
First seenMar 20, 2026

How to fix

Affected products

ProductAffected versionsFixed in
pseitz lz4_flexv < 0.11.6, 0.12.00.11.6

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