# CVE-2019-12523: Server-side request forgery in n/a

> Attackers can bypass access controls to connect to restricted internal HTTP servers, such as those listening on localhost, via URN requests.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/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:** 26 Nov 2019
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-12523, GHSA-99vq-f459-jqrg, UBUNTU-CVE-2019-12523

## What is CVE-2019-12523?

CVE-2019-12523 is a critical server-side request forgery vulnerability in Canonical Ubuntu Linux, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker can connect to HTTP servers that only listen on localhost.

## Which versions are affected by CVE-2019-12523?

It affects 5 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Opensuse Leap, Squid-Cache Squid.

## How do I fix CVE-2019-12523?

Upgrade to a fixed version.

## Is CVE-2019-12523 being exploited?

There is no known exploitation of CVE-2019-12523 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-12523 and fix it if it is affected.

What it is: CVE-2019-12523 is a critical server-side request forgery vulnerability in Canonical Ubuntu Linux, published on 26 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 CVE-2019-12523 in the wild and no public exploit code.

Affected product: Canonical Ubuntu 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-2019-12523/ (Markdown: https://insights.sbomify.com/CVE-2019-12523/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-12523
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-12523
- OSV: https://osv.dev/vulnerability/CVE-2019-12523

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-12523/
Summaries are generated and may contain mistakes; the official description above is the record.