CVE-2021-39536Public exploitNetwork attack vector

Memory corruption via unchecked sparse-matrix indexes

Published Sep 20, 2021 · Updated Aug 4, 2024

Heap-based buffer overflow in LIBXSMM through 1.16.1-93 allows context-dependent attackers to corrupt memory via crafted sparse-matrix input. The CSC and CSR readers accept row, column, and element indexes from an MTX file without checking them against allocated array bounds. A consuming application must pass attacker-controlled matrix data to the static JIT generator, where the out-of-bounds writes can crash the process or corrupt its memory.

CVSS severity8.8
High
EPSS probability1.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in LIBXSMM through 1.16.1-93 allows context-dependent attackers to corrupt memory via crafted sparse-matrix input. The CSC and CSR readers accept row, column, and element indexes from an MTX file without checking them against allocated array bounds. A consuming application must pass attacker-controlled matrix data to the static JIT generator, where the out-of-bounds writes can crash the process or corrupt its memory.

The record

CVE
CVE-2021-39536
Published
Sep 20, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002User Execution: Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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