CVE-2021-39535Network attack vector

Process crash via malformed sparse matrix data

Published Sep 20, 2021 · Updated Aug 4, 2024

NULL pointer dereference in LIBXSMM through 1.16.1-93 allows remote attackers to crash a consuming process via crafted sparse matrix data. The JIT sparse CSC and CSR readers trust declared dimensions and element coordinates when allocating and indexing internal arrays, so inconsistent input reaches an invalid pointer access. Exploitation requires an application to process attacker-supplied matrix data and is limited to terminating that process.

CVSS severity6.5
Medium
EPSS probability0.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in LIBXSMM through 1.16.1-93 allows remote attackers to crash a consuming process via crafted sparse matrix data. The JIT sparse CSC and CSR readers trust declared dimensions and element coordinates when allocating and indexing internal arrays, so inconsistent input reaches an invalid pointer access. Exploitation requires an application to process attacker-supplied matrix data and is limited to terminating that process.

The record

CVE
CVE-2021-39535
Published
Sep 20, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, 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

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

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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