# CVE-2020-15685: Command injection in Thunderbird

> Attackers can inject protocol commands during STARTTLS setup in Thunderbird, potentially leading to code execution within the encrypted session.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Dec 2022
- **Updated:** 16 Apr 2025
- **Also known as:** DEBIAN-CVE-2020-15685, GHSA-c839-4fpv-9xp7, UBUNTU-CVE-2020-15685

## What is CVE-2020-15685?

CVE-2020-15685 is a high-severity command injection vulnerability in Mozilla Thunderbird, published on 22 Dec 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

During the plaintext phase of the STARTTLS connection setup, protocol commands could have been injected and evaluated within the encrypted session. This vulnerability affects Thunderbird < 78.7.

Weakness: CWE-77 (Improper Neutralization of Special Elements used in a Command)

## Which versions are affected by CVE-2020-15685?

It affects 1 product.


Products: Mozilla Thunderbird.

## How do I fix CVE-2020-15685?

Upgrade to a fixed version.

## Is CVE-2020-15685 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-15685 exists.

## Other vulnerabilities in Mozilla Thunderbird

- [CVE-2026-92238](https://insights.sbomify.com/CVE-2026-92238/): Ambiguous parsing of mail headers (critical 9.8)
- [CVE-2026-84637](https://insights.sbomify.com/CVE-2026-84637/): Calendar invitation attachments could launch local executables (critical 9.8)
- [CVE-2021-43529](https://insights.sbomify.com/CVE-2021-43529/): Memory corruption in Thunderbird (critical 9.8)
- [CVE-2019-11703](https://insights.sbomify.com/CVE-2019-11703/): Memory corruption in Thunderbird (critical 9.8)
- [CVE-2019-11704](https://insights.sbomify.com/CVE-2019-11704/): Memory corruption in Thunderbird (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-15685 and fix it if it is affected.

What it is: CVE-2020-15685 is a high-severity command injection vulnerability in Mozilla Thunderbird, published on 22 Dec 2022. An attacker can exploit it over the internet without logging in, 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-2020-15685 exists.

Affected product: Mozilla Thunderbird. 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-2020-15685/ (Markdown: https://insights.sbomify.com/CVE-2020-15685/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-15685
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-15685
- OSV: https://osv.dev/vulnerability/CVE-2020-15685

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-15685/
Summaries are generated and may contain mistakes; the official description above is the record.