# CVE-2021-3649: Inefficient Regular Expression Complexity in chatwoot/chatwoot

> Attackers can cause denial of service in Chatwoot by exploiting inefficient regular expression complexity.

- **Severity:** High 7.5 (`CVSS:3.0/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:** 16 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-964r-mpxx-74p7

## What is CVE-2021-3649?

CVE-2021-3649 is a high-severity denial of service vulnerability in chatwoot/chatwoot, published on 16 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

chatwoot is vulnerable to Inefficient Regular Expression Complexity

Weakness: CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2021-3649?

It affects 1 product.


Products: Chatwoot Chatwoot.

## How do I fix CVE-2021-3649?

No fix has been published for CVE-2021-3649 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3649 being exploited?

There is no known exploitation of CVE-2021-3649 in the wild and no public exploit code.

## Other vulnerabilities in chatwoot/chatwoot

- [CVE-2022-3741](https://insights.sbomify.com/CVE-2022-3741/): Improper Restriction of Excessive Authentication Attempts in chatwoot/chatwoot (critical 9.4)
- [CVE-2025-21628](https://insights.sbomify.com/CVE-2025-21628/): Chatwoot has a Blind SQL-injection in Conversation and Contacts filters (critical 9.1)
- [CVE-2022-0542](https://insights.sbomify.com/CVE-2022-0542/): Cross-site Scripting (XSS) - DOM in chatwoot/chatwoot (high 8.8)
- [CVE-2022-1022](https://insights.sbomify.com/CVE-2022-1022/): Cross-site Scripting (XSS) - Stored in chatwoot/chatwoot (high 8.1)
- [CVE-2021-3742](https://insights.sbomify.com/CVE-2021-3742/): Server-Side Request Forgery (SSRF) in chatwoot/chatwoot (high 7.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3649 and fix it if it is affected.

What it is: CVE-2021-3649 is a high-severity denial of service vulnerability in chatwoot/chatwoot, published on 16 Jul 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-2021-3649 in the wild and no public exploit code.

Affected product: chatwoot/chatwoot. 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-2021-3649/ (Markdown: https://insights.sbomify.com/CVE-2021-3649/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3649
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3649
- OSV: https://osv.dev/vulnerability/CVE-2021-3649

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3649/
Summaries are generated and may contain mistakes; the official description above is the record.