Vulnerability-Lookup

CVE-2026-32829 (GCVE-0-2026-32829)

Vulnerability from cvelistv5 – Published: 2026-03-20 00:49 – Updated: 2026-03-21 03:03

Title

lz4_flex: Decompression can leak information from uninitialized memory or reused output buffer

Summary

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.

Severity ?

8.2 (High)


                        
                          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

CWE

CWE-201 - Insertion of Sensitive Information Into Sent Data
CWE-823 - Use of Out-of-range Pointer Offset

Assigner

GitHub_M

References

URL

Tags

	https://github.com/PSeitz/lz4_flex/security/advis…	x_refsource_CONFIRM
	https://github.com/PSeitz/lz4_flex/commit/055502e…	x_refsource_MISC
	https://rustsec.org/advisories/RUSTSEC-2026-0041.html	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	PSeitz	lz4_flex	Affected: < 0.11.6 Affected: >= 0.12.0, < 0.12.1

Show details on NVD website

JSON

To clipboard

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GHSA-VVP9-7P8X-RFVV

Vulnerability from github – Published: 2026-03-16 20:48 – Updated: 2026-03-20 21:18

Summary

lz4_flex's decompression can leak information from uninitialized memory or reused output buffer

Details

Summary

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

Details

The LZ4 block format defines a "match copy operation" which duplicates previously written data or data from the user-supplied dict. The position of that data is defined by an offset. The data is copied within the output buffer from the offset to the current output position. However, lz4_flex did not properly detect invalid and out-of-bounds offset values properly, causing it to copy uninitialized data from the output buffer.

Only the block based API functions are affected: lz4_flex::block::{decompress_into, decompress_into_with_dict}

When safe-decode is disabled additionally these functions are affected lz4_flex::block::{decompress, decompress_with_dict, decompress_size_prepended, decompress_size_prepended_with_dict}

All frame APIs are not affected.

There are two affected use cases: - decompressing LZ4 data with the unsafe implementation (safe-decode feature flag disabled, which is enabled by default): can leak content of uninitialized memory as decompressed result - decompressing LZ4 data into a reused, user-supplied output buffer (affects the safe-decode feature as well): can leak the previous contents of the output buffer as decompressed result

Impact

Leakage of data from uninitialized memory or content from previous decompression operations, possibly revealing sensitive information and secrets.

Mitigation

lz4_flex 0.12.1 and 0.11.6 fixes this issue without requiring changes in user code.

If you cannot upgrade, you can mitigate this vulnerability by zeroing the output buffer before calling block::decompress_into or block::decompress_into_with_dict (only block based API is affected, frame API is not affected). Additionally the the safe-decode feature flag should be enabled.

Severity ?

8.2 (High)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "lz4_flex"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
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            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "lz4_flex"
      },
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        {
          "events": [
            {
              "introduced": "0.12.0"
            },
            {
              "fixed": "0.12.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-32829"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-201",
      "CWE-823"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-16T20:48:08Z",
    "nvd_published_at": "2026-03-20T01:15:56Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nDecompressing invalid LZ4 data can leak data from uninitialized memory, or can leak content from previous decompression operations when reusing an output buffer.\n\n### Details\nThe LZ4 block format defines a \"match copy operation\" which duplicates previously written data or data from the user-supplied dict. The position of that data is defined by an _offset_. The data is copied within the output buffer from the _offset_ to the current output position.\nHowever, lz4_flex did not properly detect invalid and out-of-bounds _offset_ values properly, causing it to copy uninitialized data from the output buffer.\n\nOnly the block based API functions are affected: \n`lz4_flex::block::{decompress_into, decompress_into_with_dict}`\n\nWhen safe-decode is disabled _additionally_ these functions are affected\n`lz4_flex::block::{decompress, decompress_with_dict, decompress_size_prepended, decompress_size_prepended_with_dict}`\n\nAll `frame` APIs are _not_ affected.\n\nThere are two affected use cases:\n- decompressing LZ4 data with the `unsafe` implementation (`safe-decode` feature flag disabled, which is enabled by default):\ncan leak content of uninitialized memory as decompressed result\n- decompressing LZ4 data into a reused, user-supplied `output` buffer (affects the `safe-decode` feature as well):\ncan leak the previous contents of the output buffer as decompressed result\n\n### Impact\nLeakage of data from uninitialized memory or content from previous decompression operations, possibly revealing sensitive information and secrets.\n\n### Mitigation\nlz4_flex 0.12.1 and 0.11.6 fixes this issue without requiring changes in user code.\n\nIf you cannot upgrade, you can mitigate this vulnerability by zeroing the output buffer before calling `block::decompress_into` or  `block::decompress_into_with_dict` (only block based API is affected, frame API is not affected). Additionally the the `safe-decode` feature flag should be enabled.",
  "id": "GHSA-vvp9-7p8x-rfvv",
  "modified": "2026-03-20T21:18:54Z",
  "published": "2026-03-16T20:48:08Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/PSeitz/lz4_flex/security/advisories/GHSA-vvp9-7p8x-rfvv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-32829"
    },
    {
      "type": "WEB",
      "url": "https://github.com/PSeitz/lz4_flex/commit/055502ee5d297ecd6bf448ac91c055c7f6df9b6d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/PSeitz/lz4_flex"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0041.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "lz4_flex\u0027s decompression can leak information from uninitialized memory or reused output buffer"
}

FKIE_CVE-2026-32829

Vulnerability from fkie_nvd - Published: 2026-03-20 01:15 - Updated: 2026-03-30 15:05

Severity ?

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/PSeitz/lz4_flex/commit/055502ee5d297ecd6bf448ac91c055c7f6df9b6d	Patch
security-advisories@github.com	https://github.com/PSeitz/lz4_flex/security/advisories/GHSA-vvp9-7p8x-rfvv	Mitigation, Vendor Advisory
security-advisories@github.com	https://rustsec.org/advisories/RUSTSEC-2026-0041.html	Third Party Advisory

Impacted products

	Vendor	Product	Version
	pseitz	lz4_flex	*
	pseitz	lz4_flex	0.12.0

JSON

To clipboard

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              "versionEndExcluding": "0.11.6",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:pseitz:lz4_flex:0.12.0:*:*:*:*:rust:*:*",
              "matchCriteriaId": "2A2078FA-C55A-49B1-933D-6D7B33BB5902",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "lz4_flex es una implementaci\u00f3n pura en Rust de compresi\u00f3n/descompresi\u00f3n LZ4. En las versiones 0.11.5 e inferiores, y 0.12.0, la descompresi\u00f3n de datos LZ4 no v\u00e1lidos puede filtrar informaci\u00f3n sensible de memoria no inicializada o de operaciones de descompresi\u00f3n anteriores. La biblioteca no valida correctamente los valores de desplazamiento durante las \u0027operaciones de copia de coincidencia\u0027 de LZ4, permitiendo lecturas fuera de l\u00edmites del b\u00fafer de salida. Las funciones API basadas en bloques (\u0027decompress_into\u0027, \u0027decompress_into_with_dict\u0027, y otras cuando \u0027safe-decode\u0027 est\u00e1 deshabilitado) se ven afectadas, mientras que todas las API de trama no se ven afectadas. El impacto es la exposici\u00f3n potencial de datos sensibles y secretos a trav\u00e9s de entradas LZ4 manipuladas o malformadas. Este problema ha sido solucionado en las versiones 0.11.6 y 0.12.1."
    }
  ],
  "id": "CVE-2026-32829",
  "lastModified": "2026-03-30T15:05:23.410",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.2,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-03-20T01:15:56.277",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/PSeitz/lz4_flex/commit/055502ee5d297ecd6bf448ac91c055c7f6df9b6d"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/PSeitz/lz4_flex/security/advisories/GHSA-vvp9-7p8x-rfvv"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0041.html"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-201"
        },
        {
          "lang": "en",
          "value": "CWE-823"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

rustsec-2026-0041

Vulnerability from osv_rustsec

Published

2026-03-17 12:00

Modified

2026-03-17 16:08

Summary

Decompressing invalid data can leak information from uninitialized memory or reused output buffer

Details

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.

Severity

8.2 (High)


                    
                      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

References

URL

Type

	https://crates.io/crates/lz4_flex	PACKAGE
	https://rustsec.org/advisories/RUSTSEC-2026-0041.html	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "categories": [
          "memory-exposure"
        ],
        "cvss": "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",
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [
            "lz4_flex::block::decompress",
            "lz4_flex::block::decompress_into",
            "lz4_flex::block::decompress_into_with_dict",
            "lz4_flex::block::decompress_size_prepended",
            "lz4_flex::block::decompress_size_prepended_with_dict",
            "lz4_flex::block::decompress_with_dict"
          ],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "lz4_flex",
        "purl": "pkg:cargo/lz4_flex"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "0.11.6"
            },
            {
              "introduced": "0.12.0"
            },
            {
              "fixed": "0.12.1"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2026-32829",
    "GHSA-vvp9-7p8x-rfvv"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "Decompressing invalid LZ4 data with the block API can leak data from uninitialized memory,\nor leak content from previous decompression operations when reusing an output buffer.\n\nThe LZ4 block format defines a \"match copy operation\" which duplicates previously written\ndata or data from a user-supplied dict. The position of that data is defined by an _offset_.\n`lz4_flex` did not properly validate _offset_ values, causing it to copy data from outside\nthe initialized portion of the output buffer.\n\nTwo scenarios are affected:\n\n- Decompressing with the `unsafe` implementation (`safe-decode` feature flag disabled, which\n  is the default): can leak content of uninitialized memory as part of the decompressed result.\n- Decompressing into a reused, user-supplied output buffer (also affects `safe-decode`): can\n  leak the previous contents of the output buffer as part of the decompressed result.\n\nOnly the block-based APIs are affected. All frame APIs are unaffected.\n\nThe flaw was corrected in versions 0.11.6 and 0.12.1 by properly validating offset values\nduring decompression.\n\nIf upgrading is not possible, the issue can be mitigated by zeroing the output buffer before\neach call to the affected functions and enabling the `safe-decode` feature flag.",
  "id": "RUSTSEC-2026-0041",
  "modified": "2026-03-17T16:08:45Z",
  "published": "2026-03-17T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/lz4_flex"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0041.html"
    }
  ],
  "related": [],
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Decompressing invalid data can leak information from uninitialized memory or reused output buffer"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-32829 (GCVE-0-2026-32829)

GHSA-VVP9-7P8X-RFVV

Summary

Details

Impact

Mitigation

FKIE_CVE-2026-32829

rustsec-2026-0041

Vulnerability from osv_rustsec

Tags

Sightings

Nomenclature