# CVE-2020-10756: Information disclosure in Slirp

> A malicious guest can leak host memory contents via an out-of-bounds read in the QEMU SLiRP networking implementation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N`)
- **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:** 9 Jul 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-10756, SUSE-SU-2020:1915-1, UBUNTU-CVE-2020-10756, USN-4437-1, openSUSE-SU-2020:0987-1, openSUSE-SU-2020:0994-1

## What is CVE-2020-10756?

CVE-2020-10756 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 9 Jul 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An out-of-bounds read vulnerability was found in the SLiRP networking implementation of the QEMU emulator. This flaw occurs in the icmp6_send_echoreply() routine while replying to an ICMP echo request, also known as ping. This flaw allows a malicious guest to leak the contents of the host memory, resulting in possible information disclosure. This flaw affects versions of libslirp before 4.3.1.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2020-10756?

It affects 6 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `slirp4netns` | SUSE:Linux Enterprise Module for Containers 15 SP1 | All versions | 0.4.7-3.12.1 |
| `slirp4netns` | SUSE:Linux Enterprise Module for Containers 15 SP2 | All versions | 0.4.7-3.12.1 |
| `slirp4netns` | openSUSE:Leap 15.1 | All versions | 0.4.7-lp151.2.12.1 |
| `slirp4netns` | openSUSE:Leap 15.2 | All versions | 0.4.7-lp152.2.3.1 |

Products: Canonical Ubuntu Linux, Debian Debian Linux, Libslirp Project Libslirp, Opensuse Leap, Redhat Enterprise Linux, Redhat Openstack.

## How do I fix CVE-2020-10756?

Upgrade to a fixed version.

## Is CVE-2020-10756 being exploited?

There is no known exploitation of CVE-2020-10756 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-10756 and fix it if it is affected.

What it is: CVE-2020-10756 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 9 Jul 2020. 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-2020-10756 in the wild and no public exploit code.

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-2020-10756/ (Markdown: https://insights.sbomify.com/CVE-2020-10756/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-10756
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-10756
- OSV: https://osv.dev/vulnerability/CVE-2020-10756

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-10756/
Summaries are generated and may contain mistakes; the official description above is the record.