# CVE-2021-41495: NumPy NULL Pointer Dereference > A null pointer dereference in NumPy's sort function allows denial of service via memory exhaustion, though exploitation is practically difficult. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 17 Dec 2021 - **Updated:** 4 Aug 2024 - **Also known as:** AZL-7045, CLSA-2026-1789474848, DEBIAN-CVE-2021-41495, ECHO-02e5-0070-f939, GHSA-5545-2q6w-2gh6, MINI-q54x-3m42-wwgx, PYSEC-2021-856, RHSA-2022:8852, RHSA-2022:8861, SUSE-SU-2022:2645-1, SUSE-SU-2022:2646-1, SUSE-SU-2022:2793-1, SUSE-SU-2025:0424-1, UBUNTU-CVE-2021-41495 ## What is CVE-2021-41495? CVE-2021-41495 is a medium-severity vulnerability in n/a, published on 17 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim. ### Official description Null Pointer Dereference vulnerability exists in numpy.sort in NumPy < and 1.19 in the PyArray_DescrNew function due to missing return-value validation, which allows attackers to conduct DoS attacks by repetitively creating sort arrays. NOTE: While correct that validation is missing, an error can only occur due to an exhaustion of memory. If the user can exhaust memory, they are already privileged. Further, it should be practically impossible to construct an attack which can target the memory exhaustion to occur at exactly this place Weakness: CWE-476 (NULL Pointer Dereference) ## Which versions are affected by CVE-2021-41495? 3 open source packages ship an affected version, including numpy. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `numpy` | PyPI | All versions | 1.19 | | `numpy` | PyPI | All versions | 1.19 | | `numpy` | PyPI | All versions | 1.19.1 | | `numpy` | Red Hat:openstack:16.1::el8 | All versions | 1:1.17.0-11.el8ost | | `numpy-debugsource` | Red Hat:openstack:16.1::el8 | All versions | 1:1.17.0-11.el8ost | | `python3-numpy` | Red Hat:openstack:16.1::el8 | All versions | 1:1.17.0-11.el8ost | | `python3-numpy-debuginfo` | Red Hat:openstack:16.1::el8 | All versions | 1:1.17.0-11.el8ost | | `python3-numpy-f2py` | Red Hat:openstack:16.1::el8 | All versions | 1:1.17.0-11.el8ost | | `numpy` | Red Hat:openstack:16.2::el8 | All versions | 1:1.17.0-11.el8ost | | `numpy-debugsource` | Red Hat:openstack:16.2::el8 | All versions | 1:1.17.0-11.el8ost | | `python3-numpy` | Red Hat:openstack:16.2::el8 | All versions | 1:1.17.0-11.el8ost | | `python3-numpy-debuginfo` | Red Hat:openstack:16.2::el8 | All versions | 1:1.17.0-11.el8ost | | `python3-numpy-f2py` | Red Hat:openstack:16.2::el8 | All versions | 1:1.17.0-11.el8ost | | `python-numpy` | SUSE:Linux Enterprise Module for Basesystem 15 SP4 | All versions | 1.17.3-150400.23.3.1 | | `python3-numpy` | SUSE:Linux Enterprise Module for Basesystem 15 SP6 | All versions | 1.17.3-150400.31.1 | | `python-numpy_1_13_3-gnu-hpc` | SUSE:Linux Enterprise Module for HPC 12 | All versions | 1.13.3-4.15.1 | | `python-numpy_1_17_3-gnu-hpc` | SUSE:Linux Enterprise Module for HPC 15 SP4 | All versions | 1.17.3-150400.23.3.1 | | `python-numpy_1_17_3-gnu-hpc` | SUSE:Linux Enterprise Module for HPC 15 SP6 | All versions | 1.17.3-150400.31.1 | | `python-numpy_1_17_3-gnu-hpc` | SUSE:Linux Enterprise Module for Package Hub 15 SP6 | All versions | 1.17.3-150400.31.1 | | `python-numpy` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 1.8.0-5.14.1 | | `python-numpy` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 1.8.0-5.14.1 | | `python-numpy` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 1.8.0-5.14.1 | | `python-numpy` | openSUSE:Leap 15.4 | All versions | 1.17.3-150400.23.3.1 | | `python-numpy_1_17_3-gnu-hpc` | openSUSE:Leap 15.4 | All versions | 1.17.3-150400.23.3.1 | | `python-numpy_1_17_3-gnu-hpc` | openSUSE:Leap 15.6 | All versions | 1.17.3-150400.31.1 | | `python3-numpy` | openSUSE:Leap 15.6 | All versions | 1.17.3-150400.31.1 | Products: Numpy Numpy. ## How do I fix CVE-2021-41495? Upgrade numpy to a fixed version for your release line: 1.19 or 1.19.1. ## Is CVE-2021-41495 being exploited? There is no known exploitation of CVE-2021-41495 in the wild and no public exploit code. ## Other vulnerabilities in n/a - [CVE-2017-12852](https://insights.sbomify.com/CVE-2017-12852/): Numpy missing input validation (high 7.5) - [CVE-2021-41496](https://insights.sbomify.com/CVE-2021-41496/): Buffer Copy without Checking Size of Input in NumPy (medium 5.5) - [CVE-2014-1858](https://insights.sbomify.com/CVE-2014-1858/): Arbitrary file write in NumPy (medium 5.5) - [CVE-2021-33430](https://insights.sbomify.com/CVE-2021-33430/): NumPy Buffer Overflow (Disputed) (medium 5.3) - [CVE-2021-34141](https://insights.sbomify.com/CVE-2021-34141/): Incorrect Comparison in NumPy (medium 5.3) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-41495 and fix it if it is affected. What it is: CVE-2021-41495 is a medium-severity vulnerability in n/a, published on 17 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-41495 in the wild and no public exploit code. Affected packages and fixed versions: - numpy (PyPI): affected all versions; fixed in 1.19 - numpy (PyPI): affected all versions; fixed in 1.19 - numpy (PyPI): affected all versions; fixed in 1.19.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-41495/ (Markdown: https://insights.sbomify.com/CVE-2021-41495/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41495 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41495 - OSV: https://osv.dev/vulnerability/CVE-2021-41495 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-41495/ Summaries are generated and may contain mistakes; the official description above is the record.