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.
Affected products
pseitz: lz4 flex
References10
- github.com/PSeitz/lz4_flex/security/advisories/GHSA-vvp9-7p8x-r… MitigationVendor Advisory
- github.com/PSeitz/lz4_flex/commit/055502ee5d297ecd6bf448ac91c05… Patch
- rustsec.org/advisories/RUSTSEC-2026-0041.html Third Party Advisory
- access.redhat.com/errata/RHSA-2026:11800
- access.redhat.com/errata/RHSA-2026:16354
- access.redhat.com/errata/RHSA-2026:19712
- access.redhat.com/errata/RHSA-2026:22862
- access.redhat.com/security/cve/CVE-2026-32829
- bugzilla.redhat.com/show_bug.cgi?id=2448271
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32829…
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 4.0
-
8.2
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 51 · as of 12 November 2026
- CWE
- CWE-201CWE-823
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