# CVE-2022-33740: Information disclosure in Linux

> Linux kernel frontends fail to zero memory before sharing with backends, allowing malicious backends to read sensitive data from adjacent memory pages.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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:** 5 Jul 2022
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2022-33740, DEBIAN-CVE-2022-33740, GHSA-4v86-x4wc-r83p, UBUNTU-CVE-2022-33740

## What is CVE-2022-33740?

CVE-2022-33740 is a high-severity vulnerability in Debian Debian Linux, published on 5 Jul 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Linux disk/nic frontends data leaks T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Linux Block and Network PV device frontends don't zero memory regions before sharing them with the backend (CVE-2022-26365, CVE-2022-33740). Additionally the granularity of the grant table doesn't allow sharing less than a 4K page, leading to unrelated data residing in the same 4K page as data shared with a backend being accessible by such backend (CVE-2022-33741, CVE-2022-33742).

Weakness: CWE-212 (Improper Removal of Sensitive Information Before Storage or Transfer)

## Which versions are affected by CVE-2022-33740?

It affects 4 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Linux kernel, Xen Xen.

## How do I fix CVE-2022-33740?

Apply the vendor's patch.

## Is CVE-2022-33740 being exploited?

There is no known exploitation of CVE-2022-33740 in the wild and no public exploit code.

## 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-2022-33740 and fix it if it is affected.

What it is: CVE-2022-33740 is a high-severity vulnerability in Debian Debian Linux, published on 5 Jul 2022. 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-2022-33740 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-2022-33740/ (Markdown: https://insights.sbomify.com/CVE-2022-33740/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-33740
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-33740
- OSV: https://osv.dev/vulnerability/CVE-2022-33740

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-33740/
Summaries are generated and may contain mistakes; the official description above is the record.