# CVE-2021-41043: Use after free in tcpslice

> A use-after-free vulnerability in tcpslice can cause a crash, primarily affecting network analysts and developers using this tool.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 5 Jan 2022
- **Updated:** 4 Aug 2024
- **Also known as:** ALSA-2024:0769, ALSA-2024:2211, DEBIAN-CVE-2021-41043, GHSA-hgc7-hm7p-p5cj, RHSA-2024:0410, RHSA-2024:0571, RHSA-2024:0769, RHSA-2024:1090, RHSA-2024:2211, RLSA-2024:0769, RLSA-2024:2211, UBUNTU-CVE-2021-41043

## What is CVE-2021-41043?

CVE-2021-41043 is a medium-severity use after free vulnerability in The Tcpdump Group tcpslice, published on 5 Jan 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Use after free in tcpslice triggers AddressSanitizer, no other confirmed impact.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-41043?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `tcpdump` | AlmaLinux:8 | All versions | 14:4.9.3-3.el8_9.1.alma.1 |
| `tcpdump` | AlmaLinux:9 | All versions | 14:4.99.0-9.el9 |
| `tcpdump` | Red Hat:enterprise_linux:8::appstream | All versions | 14:4.9.3-3.el8_9.1 |
| `tcpdump-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 14:4.9.3-3.el8_9.1 |
| `tcpdump-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 14:4.9.3-3.el8_9.1 |
| `tcpdump` | Red Hat:enterprise_linux:9::appstream | All versions | 14:4.99.0-9.el9 |
| `tcpdump-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 14:4.99.0-9.el9 |
| `tcpdump-debugsource` | Red Hat:enterprise_linux:9::appstream | All versions | 14:4.99.0-9.el9 |
| `tcpdump` | Red Hat:rhel_eus:8.6::appstream | All versions | 14:4.9.3-3.el8_6.1 |
| `tcpdump-debuginfo` | Red Hat:rhel_eus:8.6::appstream | All versions | 14:4.9.3-3.el8_6.1 |
| `tcpdump-debugsource` | Red Hat:rhel_eus:8.6::appstream | All versions | 14:4.9.3-3.el8_6.1 |
| `tcpdump` | Red Hat:rhel_eus:8.8::appstream | All versions | 14:4.9.3-3.el8_8.1 |
| `tcpdump-debuginfo` | Red Hat:rhel_eus:8.8::appstream | All versions | 14:4.9.3-3.el8_8.1 |
| `tcpdump-debugsource` | Red Hat:rhel_eus:8.8::appstream | All versions | 14:4.9.3-3.el8_8.1 |
| `tcpdump` | Red Hat:rhel_eus:9.2::appstream | All versions | 14:4.99.0-6.el9_2.1 |
| `tcpdump-debuginfo` | Red Hat:rhel_eus:9.2::appstream | All versions | 14:4.99.0-6.el9_2.1 |
| `tcpdump-debugsource` | Red Hat:rhel_eus:9.2::appstream | All versions | 14:4.99.0-6.el9_2.1 |
| `tcpdump` | Rocky Linux:8 | All versions | 4:4.9.3-3.el8_9.1 |
| `tcpdump` | Rocky Linux:9 | All versions | 4:4.99.0-9.el9 |

Products: Tcpdump Tcpslice.

## How do I fix CVE-2021-41043?

Apply the vendor's patch.

## Is CVE-2021-41043 being exploited?

There is no known exploitation of CVE-2021-41043 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41043 and fix it if it is affected.

What it is: CVE-2021-41043 is a medium-severity use after free vulnerability in The Tcpdump Group tcpslice, published on 5 Jan 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-41043 in the wild and no public exploit code.

Affected product: The Tcpdump Group tcpslice. 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-2021-41043/ (Markdown: https://insights.sbomify.com/CVE-2021-41043/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41043
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41043
- OSV: https://osv.dev/vulnerability/CVE-2021-41043

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41043/
Summaries are generated and may contain mistakes; the official description above is the record.