# CVE-2021-33580: regex injection leading to DoS

> An attacker can cause a denial of service via regex catastrophic backtracking by sending crafted HTTP headers to Apache Roller.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Aug 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-x9w7-f6x8-r9xh

## What is CVE-2021-33580?

CVE-2021-33580 is a high-severity denial of service vulnerability in Apache Roller, published on 18 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

User controlled `request.getHeader("Referer")`, `request.getRequestURL()` and `request.getQueryString()` are used to build and run a regex expression. The attacker doesn't have to use a browser and may send a specially crafted Referer header programmatically. Since the attacker controls the string and the regex pattern he may cause a ReDoS by regex catastrophic backtracking on the server side. This problem has been fixed in Roller 6.0.2.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2021-33580?

It affects 1 product.


Products: Apache Roller.

## How do I fix CVE-2021-33580?

No fix has been published for CVE-2021-33580 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-33580 being exploited?

There is no known exploitation of CVE-2021-33580 in the wild and no public exploit code.

## Other vulnerabilities in Apache Roller

- [CVE-2018-17198](https://insights.sbomify.com/CVE-2018-17198/): Server-side request forgery in Apache Roller (critical 9.8)
- [CVE-2014-0030](https://insights.sbomify.com/CVE-2014-0030/): XML external entity in n/a (critical 9.8)
- [CVE-2015-0249](https://insights.sbomify.com/CVE-2015-0249/): Code injection in n/a (high 7.2)
- [CVE-2013-4212](https://insights.sbomify.com/CVE-2013-4212/): Code injection in n/a (medium 6.8)
- [CVE-2012-2380](https://insights.sbomify.com/CVE-2012-2380/): Cross-site request forgery in n/a (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33580 and fix it if it is affected.

What it is: CVE-2021-33580 is a high-severity denial of service vulnerability in Apache Roller, published on 18 Aug 2021. 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-2021-33580 in the wild and no public exploit code.

Affected product: Apache Roller. 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-2021-33580/ (Markdown: https://insights.sbomify.com/CVE-2021-33580/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33580
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33580
- OSV: https://osv.dev/vulnerability/CVE-2021-33580

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33580/
Summaries are generated and may contain mistakes; the official description above is the record.