# CVE-2020-12398: Security feature bypass in Thunderbird

> Attackers can intercept email data if Thunderbird is configured for STARTTLS but the server sends a PREAUTH response, bypassing encryption.

- **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 Jul 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-12398, GHSA-jvxv-vphc-73rg, UBUNTU-CVE-2020-12398

## What is CVE-2020-12398?

CVE-2020-12398 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 9 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

If Thunderbird is configured to use STARTTLS for an IMAP server, and the server sends a PREAUTH response, then Thunderbird will continue with an unencrypted connection, causing email data to be sent without protection. This vulnerability affects Thunderbird < 68.9.0.

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

## Which versions are affected by CVE-2020-12398?

It affects 2 products.


Products: Canonical Ubuntu Linux, Mozilla Thunderbird.

## How do I fix CVE-2020-12398?

Upgrade to a fixed version.

## Is CVE-2020-12398 being exploited?

There is no known exploitation of CVE-2020-12398 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-2020-12398 and fix it if it is affected.

What it is: CVE-2020-12398 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 9 Jul 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-2020-12398 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-2020-12398/ (Markdown: https://insights.sbomify.com/CVE-2020-12398/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12398
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12398
- OSV: https://osv.dev/vulnerability/CVE-2020-12398

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-12398/
Summaries are generated and may contain mistakes; the official description above is the record.