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CVE Record

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

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.

HighCVSS 8.2Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-32829 affects the Rust lz4_flex library. When some block decompression APIs process malformed LZ4 data, they may expose sensitive bytes from memory or a prior decompression buffer. This is a confidentiality issue, not a code-execution claim. Fixed versions are available.

Executive priority

Prioritize remediation for internet-facing or multi-tenant services that decompress untrusted LZ4 data. The business risk is secret or customer data exposure through memory disclosure, with no active exploitation evidence in the provided sources.

Technical view

lz4_flex versions below 0.11.6 and 0.12.0 before 0.12.1 may fail to validate offsets during LZ4 match copy operations, causing out-of-bounds reads from the output buffer. Affected paths include block APIs such as decompress_into and decompress_into_with_dict. Frame APIs are reported unaffected.

Likely exposure

Exposure is most likely in Rust applications or products that depend on affected lz4_flex versions and decompress attacker-controlled or untrusted LZ4 block data. Systems using only frame APIs are not indicated as affected by the provided sources.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation depends on crafted or malformed LZ4 input reaching affected block-based decompression APIs. The stated impact is potential disclosure of sensitive data or secrets.

Researcher notes

Focus triage on block API call sites and dependency paths. The vulnerable condition is invalid offset handling during match copy operations. Do not assume frame API impact from the provided evidence. Confirm whether safe-decode is disabled for any relevant path.

Mitigation direction

  • Upgrade lz4_flex to 0.11.6 or 0.12.1 or later.
  • Refresh Cargo.lock and rebuild deployed artifacts.
  • Avoid affected block decompression APIs for untrusted input until upgraded.
  • Keep safe-decode enabled where applicable.
  • Review linked Red Hat advisories for packaged product remediation.

Validation and detection

  • Check Cargo.toml and Cargo.lock for lz4_flex versions.
  • Identify use of decompress_into, decompress_into_with_dict, and related block APIs.
  • Confirm whether compressed input can be user-supplied or network-supplied.
  • Run dependency scanning against RustSec advisory RUSTSEC-2026-0041.
  • Verify production artifacts include fixed lz4_flex versions.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-201: Information exposure and cloud metadata lookup

Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · low confidence lookup

CWE-823: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-32829 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.2 (4.0)
Known Exploited
No
Published

Vector: 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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
11Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.2CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N——GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.2High
CVSS 4.0 vector shape for CVE-2026-32829Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: 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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. ADP timelineredhat-SADP

    Reported to Red Hat.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPlz4_flex: lz4_flex's decompression can leak information from uninitialized memory or reused output buffer
other:Red Hat severity ratingcvssV3_1
  • 2026-03-16T22:05:38.553Z: Reported to Red Hat.
  • 2026-03-16T20:48:08.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
PSeitzlz4_flex< 0.11.6, >= 0.12.0, < 0.12.1Listed
Weakness

CWE details

CWE-201CWE-823

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-201 · source CWE mapping

Insertion of Sensitive Information Into Sent Data

Insertion of Sensitive Information Into Sent Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-823 · source CWE mapping

Use of Out-of-range Pointer Offset

Use of Out-of-range Pointer Offset represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs