# CVE-2020-15953: Other in n/a

> A STARTTLS buffering flaw in LibEtPan allows attackers to inject responses into the TLS context, bypassing security checks.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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:** 27 Jul 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-15953, DLA-2329-1, GHSA-f329-rp43-94r4, MGASA-2020-0366, UBUNTU-CVE-2020-15953, USN-4598-1, openSUSE-SU-2020:1454-1, openSUSE-SU-2020:1505-1

## What is CVE-2020-15953?

CVE-2020-15953 is a high-severity vulnerability in Debian Debian Linux, published on 27 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

LibEtPan through 1.9.4, as used in MailCore 2 through 0.6.3 and other products, has a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a "begin TLS" response, the client reads additional data (e.g., from a meddler-in-the-middle attacker) and evaluates it in a TLS context, aka "response injection."

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2020-15953?

It affects 4 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libetpan` | SUSE:Package Hub 15 SP2 | All versions | 1.9.4-bp152.4.3.1 |
| `libetpan` | openSUSE:Leap 15.2 | All versions | 1.9.4-lp152.3.3.1 |

Products: Debian Debian Linux, Fedoraproject Fedora, Libetpan Project Libetpan, Libmailcore Mailcore2.

## How do I fix CVE-2020-15953?

Upgrade to a fixed version.

## Is CVE-2020-15953 being exploited?

There is no known exploitation of CVE-2020-15953 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-15953 and fix it if it is affected.

What it is: CVE-2020-15953 is a high-severity vulnerability in Debian Debian Linux, published on 27 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-2020-15953 in the wild and no public exploit code.

Affected product: Debian Debian 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-2020-15953/ (Markdown: https://insights.sbomify.com/CVE-2020-15953/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-15953
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-15953
- OSV: https://osv.dev/vulnerability/CVE-2020-15953

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-15953/
Summaries are generated and may contain mistakes; the official description above is the record.