# CVE-2021-3347: Use after free in n/a > Local attackers can exploit a use-after-free in PI futexes to execute arbitrary code in the kernel, leading to privilege escalation. - **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 29 Jan 2021 - **Updated:** 25 Feb 2026 - **Also known as:** A-171705902, ASB-A-171705902, DEBIAN-CVE-2021-3347, GHSA-8r42-h5pm-2vw2, MGASA-2021-0062, RHSA-2021:2285, UBUNTU-CVE-2021-3347 ## What is CVE-2021-3347? CVE-2021-3347 is a high-severity use after free vulnerability in Debian Debian Linux, published on 29 Jan 2021. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description An issue was discovered in the Linux kernel through 5.10.11. PI futexes have a kernel stack use-after-free during fault handling, allowing local users to execute code in the kernel, aka CID-34b1a1ce1458. Weakness: CWE-416 (Use After Free) ## Which versions are affected by CVE-2021-3347? It affects 3 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `kpatch-patch-3_10_0-1160` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | | `kpatch-patch-3_10_0-1160-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | | `kpatch-patch-3_10_0-1160_11_1` | Red Hat:enterprise_linux:7::server | All versions | 0:1-5.el7 | | `kpatch-patch-3_10_0-1160_11_1-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-5.el7 | | `kpatch-patch-3_10_0-1160_15_2` | Red Hat:enterprise_linux:7::server | All versions | 0:1-5.el7 | | `kpatch-patch-3_10_0-1160_15_2-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-5.el7 | | `kpatch-patch-3_10_0-1160_21_1` | Red Hat:enterprise_linux:7::server | All versions | 0:1-3.el7 | | `kpatch-patch-3_10_0-1160_21_1-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-3.el7 | | `kpatch-patch-3_10_0-1160_24_1` | Red Hat:enterprise_linux:7::server | All versions | 0:1-1.el7 | | `kpatch-patch-3_10_0-1160_24_1-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-1.el7 | | `kpatch-patch-3_10_0-1160_25_1` | Red Hat:enterprise_linux:7::server | All versions | 0:1-1.el7 | | `kpatch-patch-3_10_0-1160_25_1-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-1.el7 | | `kpatch-patch-3_10_0-1160_2_1` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | | `kpatch-patch-3_10_0-1160_2_1-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | | `kpatch-patch-3_10_0-1160_2_2` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | | `kpatch-patch-3_10_0-1160_2_2-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | | `kpatch-patch-3_10_0-1160_6_1` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | | `kpatch-patch-3_10_0-1160_6_1-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1-6.el7 | Products: Debian Debian Linux, Fedoraproject Fedora, Linux kernel. ## How do I fix CVE-2021-3347? Apply the vendor's patch. ## Is CVE-2021-3347 being exploited? It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-3347 exists. Public exploit code: - https://github.com/nanopathi/linux-4.19.72_CVE-2021-3347 (github_poc): https://github.com/nanopathi/linux-4.19.72_CVE-2021-3347 ## Other vulnerabilities in Debian Debian Linux - [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild) - [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild) - [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild) - [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild) - [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-3347 and fix it if it is affected. What it is: CVE-2021-3347 is a high-severity use after free vulnerability in Debian Debian Linux, published on 29 Jan 2021. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-3347 exists. Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page. 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-2021-3347/ (Markdown: https://insights.sbomify.com/CVE-2021-3347/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3347 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3347 - OSV: https://osv.dev/vulnerability/CVE-2021-3347 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-3347/ Summaries are generated and may contain mistakes; the official description above is the record.