# CVE-2019-7303: Snapd seccomp filter TIOCSTI ioctl bypass

> A flaw in snapd's seccomp filters allows strict mode snaps to bypass terminal restrictions and inject characters into the host terminal.

- **Severity:** Medium 5.7 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Apr 2019
- **Updated:** 17 Sep 2024
- **Also known as:** DEBIAN-CVE-2019-7303, GHSA-hhhq-qgvm-w5hp, UBUNTU-CVE-2019-7303, USN-3917-1

## What is CVE-2019-7303?

CVE-2019-7303 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 23 Apr 2019. 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

A vulnerability in the seccomp filters of Canonical snapd before version 2.37.4 allows a strict mode snap to insert characters into a terminal on a 64-bit host. The seccomp rules were generated to match 64-bit ioctl(2) commands on a 64-bit platform; however, the Linux kernel only uses the lower 32 bits to determine which ioctl(2) commands to run. This issue affects: Canonical snapd versions prior to 2.37.4.

Weakness: CWE-628 (Function Call with Incorrectly Specified Arguments)

## Which versions are affected by CVE-2019-7303?

It affects 2 products.


Products: Canonical Snapd, Canonical Ubuntu Linux.

## How do I fix CVE-2019-7303?

Upgrade to a fixed version.

## Is CVE-2019-7303 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-7303 exists.

Public exploit code:

- snap - seccomp BBlacklist for TIOCSTI can be Circumvented (exploitdb)

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2023-1523](https://insights.sbomify.com/CVE-2023-1523/): Command injection in snapd (critical 10.0)
- [CVE-2020-27352](https://insights.sbomify.com/CVE-2020-27352/): Privilege escalation in snapd (critical 9.3)
- [CVE-2019-7304](https://insights.sbomify.com/CVE-2019-7304/): Local privilege escalation via snapd socket (high 8.8)
- [CVE-2021-4120](https://insights.sbomify.com/CVE-2021-4120/): snapd could be made to bypass intended access restrictions through snap content interfaces and layout paths (high 8.2)
- [CVE-2024-5138](https://insights.sbomify.com/CVE-2024-5138/): CVE-2024-5138: snapd snapctl auth bypass (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-7303 and fix it if it is affected.

What it is: CVE-2019-7303 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 23 Apr 2019. 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-7303 exists.

Affected product: Canonical Ubuntu 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-2019-7303/ (Markdown: https://insights.sbomify.com/CVE-2019-7303/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-7303
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-7303
- OSV: https://osv.dev/vulnerability/CVE-2019-7303

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-7303/
Summaries are generated and may contain mistakes; the official description above is the record.