# PSF-2019-14: Regular Expression Denial of Service in http.cookiejar

> A malicious HTTP server can cause extreme CPU usage and block execution in Python applications parsing Set-Cookie headers via a vulnerable regex.

- **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:** 14 Nov 2019

## What is PSF-2019-14?

PSF-2019-14 is a denial of service vulnerability, published on 14 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The regex ``http.cookiejar.LOOSE_HTTP_DATE_RE`` is vulnerable to regular
expression denial of service ("REDoS"). ``LOOSE_HTTP_DATE_RE.match()`` is
called when using ``http.cookiejar.CookieJar`` to parse ``Set-Cookie``
headers returned by a HTTP server. Processing a response from a malicious
HTTP server can lead to extreme CPU usage and execution will be blocked
for a long time.

## Which versions are affected by PSF-2019-14?


## How do I fix PSF-2019-14?

No fix has been published for PSF-2019-14 yet. Limit exposure of the affected software until one is available.

## Is PSF-2019-14 being exploited?

There is no known exploitation of PSF-2019-14 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for PSF-2019-14 and fix it if it is affected.

What it is: PSF-2019-14 is a denial of service vulnerability, published on 14 Nov 2019. 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-2019-14 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-2019-14/ (Markdown: https://insights.sbomify.com/PSF-2019-14/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/PSF-2019-14

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From sbomify Insights: https://insights.sbomify.com/PSF-2019-14/
Summaries are generated and may contain mistakes; the official description above is the record.