CVE-2021-41495

Interpreter crash via unchecked descriptor allocation

Published Dec 17, 2021 · Updated Aug 4, 2024

Null pointer dereference in NumPy before 1.19.1 allows attackers to crash the Python interpreter by repeatedly creating sort arrays. PyArray_DescrNew can return NULL after an allocation failure, and a numpy.sort call site reads the returned descriptor without checking it. Triggering the dereference requires memory exhaustion at that exact allocation point and permission to execute NumPy functions, so NumPy disputes that the bug crosses a security boundary beyond the caller's existing process privileges.

CVSS severity5.3
Medium
EPSS probability1.15%
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 NumPy before 1.19.1 allows attackers to crash the Python interpreter by repeatedly creating sort arrays. PyArray_DescrNew can return NULL after an allocation failure, and a numpy.sort call site reads the returned descriptor without checking it. Triggering the dereference requires memory exhaustion at that exact allocation point and permission to execute NumPy functions, so NumPy disputes that the bug crosses a security boundary beyond the caller's existing process privileges.

The record

CVE
CVE-2021-41495
Published
Dec 17, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 17, 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 vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.3NVDCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
3.5NVDAV:N/AC:M/Au:S/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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