# CVE-2020-1749: Information disclosure in kernel

> An attacker can read unencrypted traffic in IPsec VXLAN/GENEVE tunnels over IPv6 due to incorrect kernel routing, compromising data confidentiality.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Sep 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-1749, GHSA-pw98-cq7c-645p, SUSE-SU-2020:0891-1, SUSE-SU-2020:1049-1, UBUNTU-CVE-2020-1749

## What is CVE-2020-1749?

CVE-2020-1749 is a high-severity vulnerability in Linux kernel, published on 9 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in the Linux kernel's implementation of some networking protocols in IPsec, such as VXLAN and GENEVE tunnels over IPv6. When an encrypted tunnel is created between two hosts, the kernel isn't correctly routing tunneled data over the encrypted link; rather sending the data unencrypted. This would allow anyone in between the two endpoints to read the traffic unencrypted. The main threat from this vulnerability is to data confidentiality.

Weakness: CWE-319 (Cleartext Transmission of Sensitive Information)

## Which versions are affected by CVE-2020-1749?

It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kgraft-patch-SLE12-SP4_Update_12` | SUSE:Linux Enterprise Live Patching 12 SP4 | All versions | 2-2.1 |
| `kgraft-patch-SLE12-SP5_Update_3` | SUSE:Linux Enterprise Live Patching 12 SP5 | All versions | 2-2.1 |
| `kernel-livepatch-SLE15-SP1_Update_10` | SUSE:Linux Enterprise Live Patching 15 SP1 | All versions | 2-2.2 |
| `kernel-livepatch-SLE15-SP1_Update_9` | SUSE:Linux Enterprise Live Patching 15 SP1 | All versions | 2-2.1 |

Products: Linux kernel, Redhat Enterprise Linux, Redhat Enterprise Mrg.

## How do I fix CVE-2020-1749?

Apply the vendor's patch.

## Is CVE-2020-1749 being exploited?

There is no known exploitation of CVE-2020-1749 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-1749 and fix it if it is affected.

What it is: CVE-2020-1749 is a high-severity vulnerability in Linux kernel, published on 9 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-1749 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2020-1749/ (Markdown: https://insights.sbomify.com/CVE-2020-1749/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1749
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1749
- OSV: https://osv.dev/vulnerability/CVE-2020-1749

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1749/
Summaries are generated and may contain mistakes; the official description above is the record.