# CVE-2020-12063: Security feature bypass in n/a

> Attackers can bypass sender login restrictions in Postfix by using homoglyph characters in email addresses, allowing spoofed outbound messages.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Apr 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-5wj2-9pm2-74vm

## What is CVE-2020-12063?

CVE-2020-12063 is a medium-severity vulnerability in n/a, published on 24 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A certain Postfix 2.10.1-7 package could allow an attacker to send an email from an arbitrary-looking sender via a homoglyph attack, as demonstrated by the similarity of \xce\xbf to the 'o' character. This is potentially relevant when the /etc/postfix/sender_login feature is used, because a spoofed outbound message that uses a configured sender address is blocked with a "Sender address rejected: not logged in" error message, but a spoofed outbound message that uses a homoglyph of a configured sender address is not blocked. NOTE: some third parties argue that any missed blocking of spoofed outbound messages - except for exact matches to a sender address in the /etc/postfix/sender_login file - is outside the design goals of Postfix and thus cannot be considered a Postfix vulnerability

## Which versions are affected by CVE-2020-12063?

It affects 1 product.


Products: Postfix Postfix.

## How do I fix CVE-2020-12063?

No fix has been published for CVE-2020-12063 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-12063 being exploited?

There is no known exploitation of CVE-2020-12063 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2017-10140](https://insights.sbomify.com/CVE-2017-10140/): Privilege escalation in n/a (high 7.8)
- [CVE-2009-2939](https://insights.sbomify.com/CVE-2009-2939/): Path traversal in n/a (medium 6.9)
- [CVE-2008-4977](https://insights.sbomify.com/CVE-2008-4977/): Path traversal in n/a (medium 6.9)
- [CVE-2011-1720](https://insights.sbomify.com/CVE-2011-1720/): Memory corruption in n/a (medium 6.8)
- [CVE-2011-0411](https://insights.sbomify.com/CVE-2011-0411/): Security feature bypass in n/a (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-12063 and fix it if it is affected.

What it is: CVE-2020-12063 is a medium-severity vulnerability in n/a, published on 24 Apr 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-2020-12063 in the wild and no public exploit code.

Affected product: n/a. 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-2020-12063/ (Markdown: https://insights.sbomify.com/CVE-2020-12063/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12063
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12063
- OSV: https://osv.dev/vulnerability/CVE-2020-12063

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-12063/
Summaries are generated and may contain mistakes; the official description above is the record.