# CVE-2019-12524: Security feature bypass in n/a

> Attackers can bypass URL regex restrictions to access the Cache Manager and view sensitive server information in Squid.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Apr 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-12524, GHSA-wwv6-9vqw-fwxx, UBUNTU-CVE-2019-12524

## What is CVE-2019-12524?

CVE-2019-12524 is a critical vulnerability in Canonical Ubuntu Linux, published on 15 Apr 2020. 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 through 4.7. When handling requests from users, Squid checks its rules to see if the request should be denied. Squid by default comes with rules to block access to the Cache Manager, which serves detailed server information meant for the maintainer. This rule is implemented via url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to encode their URL to bypass the url_regex check, and gain access to the blocked resource.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2019-12524?

It affects 3 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Squid-Cache Squid.

## How do I fix CVE-2019-12524?

Upgrade to a fixed version.

## Is CVE-2019-12524 being exploited?

There is no known exploitation of CVE-2019-12524 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-2019-12524 and fix it if it is affected.

What it is: CVE-2019-12524 is a critical vulnerability in Canonical Ubuntu Linux, published on 15 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-2019-12524 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-2019-12524/ (Markdown: https://insights.sbomify.com/CVE-2019-12524/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-12524
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-12524
- OSV: https://osv.dev/vulnerability/CVE-2019-12524

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-12524/
Summaries are generated and may contain mistakes; the official description above is the record.