# PSF-2018-8: Email folding function Denial-of-Service

> An attacker can cause a denial of service by sending emails with long headers containing many non-ASCII characters, triggering an infinite loop in the email folding function.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 May 2018

## What is PSF-2018-8?

PSF-2018-8 is a denial of service vulnerability, published on 16 May 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The email folding function enters an infinite loop if a header is longer
than the policy maximum line length and contains many non-ASCII characters.

Regression introduced in Python 3.6.4.

## Which versions are affected by PSF-2018-8?


## How do I fix PSF-2018-8?

No fix has been published for PSF-2018-8 yet. Limit exposure of the affected software until one is available.

## Is PSF-2018-8 being exploited?

There is no known exploitation of PSF-2018-8 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for PSF-2018-8 and fix it if it is affected.

What it is: PSF-2018-8 is a denial of service vulnerability, published on 16 May 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of PSF-2018-8 in the wild and no public exploit code.

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/PSF-2018-8/ (Markdown: https://insights.sbomify.com/PSF-2018-8/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/PSF-2018-8

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From sbomify Insights: https://insights.sbomify.com/PSF-2018-8/
Summaries are generated and may contain mistakes; the official description above is the record.