CVE-2026-32829 — lz4_flex: Decompression can leak information from uninitialized memory or reused output buffer

Affected: PSeitz lz4_flex, Red Hat Logging Subsystem for Red Hat OpenShift 6.2, Red Hat Logging Subsystem for Red Hat OpenShift 6.4, Red Hat Logging Subsystem for Red Hat OpenShift 6.5, Red Hat OpenShift AI 3.3, Red Hat OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift AI (RHOAI)

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.

RUSTSEC-2026-0041 — Decompressing invalid data can leak information from uninitialized memory or reused output buffer

Affected: crates.io: lz4_flex

Decompressing invalid LZ4 data with the block API can leak data from uninitialized memory, or leak content from previous decompression operations when reusing an output buffer.

The LZ4 block format defines a "match copy operation" which duplicates previously written data or data from a user-supplied dict. The position of that data is defined by an _offset_. `lz4_flex` did not properly validate _offset_ values, causing it to copy data from outside the initialized portion of the output buffer.

Two scenarios are affected:

- Decompressing with the `unsafe` implementation (`safe-decode` feature flag disabled, which is the default): can leak content of uninitialized memory as part of the decompressed result. - Decompressing into a reused, user-supplied output buffer (also affects `safe-decode`): can leak the previous contents of the output buffer as part of the decompressed result.

Only the block-based APIs are affected. All frame APIs are unaffected.

The flaw was corrected in versions 0.11.6 and 0.12.1 by properly validating offset values during decompression.

If upgrading is not possible, the issue can be mitigated by zeroing the output buffer before each call to the affected functions and enabling the `safe-decode` feature flag.

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CVE-2026-32829 — lz4_flex: Decompression can leak information from uninitialized memory or reused output buffer

RUSTSEC-2026-0041 — Decompressing invalid data can leak information from uninitialized memory or reused output buffer