# CVE-2021-27365: Memory corruption in n/a

> An unprivileged user can trigger memory corruption in the Linux kernel via oversized iSCSI Netlink messages, potentially leading to code execution or 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:** 7 Mar 2021
- **Updated:** 3 Aug 2024
- **Also known as:** AZL-6534, DEBIAN-CVE-2021-27365, GHSA-qwp9-8pwv-6hg4, UBUNTU-CVE-2021-27365

## What is CVE-2021-27365?

CVE-2021-27365 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 7 Mar 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 5.11.3. Certain iSCSI data structures do not have appropriate length constraints or checks, and can exceed the PAGE_SIZE value. An unprivileged user can send a Netlink message that is associated with iSCSI, and has a length up to the maximum length of a Netlink message.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-27365?

It affects 5 products.


Products: Debian Debian Linux, Linux kernel, Netapp Cloud Backup, Netapp Solidfire Baseboard Management Controller Firmware, Oracle Tekelec Platform Distribution.

## How do I fix CVE-2021-27365?

Apply the vendor's patch.

## Is CVE-2021-27365 being exploited?

There is no known exploitation of CVE-2021-27365 in the wild and no public exploit code.

Public exploit code:

- https://github.com/WhatsWrongAndWhy/CVE-2021-27365 (github_poc): https://github.com/WhatsWrongAndWhy/CVE-2021-27365

## 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-2021-27365 and fix it if it is affected.

What it is: CVE-2021-27365 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 7 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-27365 in the wild and no public exploit code.

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-2021-27365/ (Markdown: https://insights.sbomify.com/CVE-2021-27365/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27365
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27365
- OSV: https://osv.dev/vulnerability/CVE-2021-27365

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27365/
Summaries are generated and may contain mistakes; the official description above is the record.