CVE-2020-29367: Blosc2 Blosc2 Heap-based Buffer Overflow Vulnerability

HIGH
Advisory Identifier: GHSA-8c7c-2c8j-3xfp
Share
CVSS 7.8
CWE-787
Published
Advisory Summary

CVE-2020-29367 is a HIGH (CVSS 7.8) blosc2 heap-based buffer overflow vulnerability (CWE-787: Out-of-bounds Write) affecting Blosc2 libraries in the PyPI ecosystem. The issue involves blosc2 heap-based buffer overflow. Remediation is available by upgrading affected packages to version 0.1.7.

CVE-2020-29367 at a Glance

CVE Identifier CVE-2020-29367
GHSA Identifier GHSA-8c7c-2c8j-3xfp
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification CWE-787: Out-of-bounds Write
Affected Product Blosc2
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2020-29367

To remediate this vulnerability, upgrade all affected Blosc2 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

blosc2 fixed: 0.1.7 
pip install blosc2>=0.1.7
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show blosc2

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2020-29367, inspect your installed packages using pip:

pip show blosc2

Analyze the terminal output to locate any version of Blosc2 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.1.7), your application is affected.

Note: The pip show blosc2 command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-787: Out-of-bounds Write, where the product writes data past the end, or before the beginning, of the intended buffer. In Blosc2, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

blosc2.c in Blosc C-Blosc2 through 2.0.0.beta.5 has a heap-based buffer overflow when there is a lack of space to write compressed data.

CVE-2020-29367 Affected Blosc2 Versions

1 component(s)
Fixed Versions:
0.1.7
Product / Package Ecosystem Affected Versions Fixed Version
blosc2
pypi/blosc2
PyPI
< 0.1.7
0.1.7

References

NVD — CVE-2020-29367 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-29367
Security Fix Commit FIX COMMIT
https://github.com/Blosc/c-blosc2/commit/c4c6470e88210afc95262c8b9fcc27e30ca043ee
bugs.chromium.org/p/oss-fuzz/issues/d... WEB
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26442
Blosc2 Source Repository REPOSITORY
https://github.com/Blosc/python-blosc2
Blosc2 Release RELEASE
https://github.com/Blosc/python-blosc2/releases/tag/v0.1.7
Blosc2 Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/blosc2/PYSEC-2020-343.yaml

Frequently Asked Questions

What is CVE-2020-29367?
CVE-2020-29367 is a security vulnerability in Blosc2 involving blosc2 heap-based buffer overflow under CWE-787: Out-of-bounds Write.
Which Blosc2 versions are affected?
Affected versions include releases prior to 0.1.7 across affected packages: blosc2.
What version fixes CVE-2020-29367?
Upgrading to 0.1.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is blosc2 affected?
Yes, blosc2 is affected in releases prior to 0.1.7. Upgrade your dependency to 0.1.7 or later.
What is the CVSS score of CVE-2020-29367?
CVE-2020-29367 has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2020-29367?
CVE-2020-29367 is classified under CWE-787: Out-of-bounds Write (The product writes data past the end, or before the beginning, of the intended buffer.).
How can I check PyPI dependencies for CVE-2020-29367?
Run the dependency tree command: 'pip show blosc2'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8c7c-2c8j-3xfp",
  "modified" : "2026-06-10T18:42:41Z",
  "published" : "2022-05-24T17:35:03Z",
  "aliases" : [ "CVE-2020-29367" ],
  "summary" : "blosc2 heap-based buffer overflow",
  "details" : "blosc2.c in Blosc C-Blosc2 through 2.0.0.beta.5 has a heap-based buffer overflow when there is a lack of space to write compressed data.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "blosc2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.1.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-29367"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Blosc/c-blosc2/commit/c4c6470e88210afc95262c8b9fcc27e30ca043ee"
  }, {
    "type" : "WEB",
    "url" : "https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26442"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Blosc/python-blosc2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Blosc/python-blosc2/releases/tag/v0.1.7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/blosc2/PYSEC-2020-343.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-787" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-11-21T22:19:07Z",
    "nvd_published_at" : "2020-11-27T20:15:00Z"
  }
}