CVE-2020-5249 HTTP Response Splitting (Early Hints) in Puma
Attackers can inject malicious content via HTTP response splitting in Puma's early-hints headers if untrusted input is allowed, enabling XSS or header injection.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2020-5249?
CVE-2020-5249 is a medium-severity vulnerability in Puma, published on 2 Mar 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
In Puma (RubyGem) before 4.3.3 and 3.12.4, if an application using Puma allows untrusted input in an early-hints header, an attacker can use a carriage return character to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as HTTP Response Splitting. While not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS). This is related to CVE-2020-5247, which fixed this vulnerability but only for regular responses. This has been fixed in 4.3.3 and 3.12.4.
Which versions are affected by CVE-2020-5249?
4 open source packages ship an affected version, including puma. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
puma RubyGems | All versions | 3.12.4 |
puma RubyGems | All versions | 3.12.4 |
puma RubyGems | From 4.0.0 | 4.3.3 |
puma RubyGems | From 4.0.0 | 4.3.3 |
Products include Puma Puma.
How do I fix CVE-2020-5249?
Upgrade puma to a fixed version for your release line: 3.12.4 or 4.3.3.
Is CVE-2020-5249 being exploited?
There is no known exploitation of CVE-2020-5249 in the wild and no public exploit code.
Other vulnerabilities in Puma
Sources
Also known as DEBIAN-CVE-2020-5249, GHSA-33vf-4xgg-9r58.