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CVE-2020-11076 High

HTTP Smuggling via Transfer-Encoding Header in Puma

### Impact By using an invalid transfer-encoding header, an attacker could [smuggle an HTTP response.](https://portswigger.net/web-security/request-smuggling) Originally reported by @ZeddYu, who has our thanks for the detailed report. ### Patches The problem has been fixed in Puma 3.12.5 and Puma 4.3.4. ### For more information If you have any questions or comments about this advisory: * Open an issue in [Puma](https://github.com/puma/puma) * See our [security policy](https://github.com/puma/puma/security/policy)

Exploit probability 4.0%
Published May 22, 2020
Required by Not available
Last source change March 13, 2026

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

38 explicit affected versions

RubyGems puma

116 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities GHSA-x7jg-6pwg-fx5h

### Impact By using an invalid transfer-encoding header, an attacker could [smuggle an HTTP response.](https://portswigger.net/web-security/request-smuggling) Originally reported by @ZeddYu, who has our thanks for the detailed report. ### Patches The problem has been fixed in Puma 3.12.5 and Puma 4.3.4. ### For more information If you have any questions or comments about this advisory: * Open an issue in [Puma](https://github.com/puma/puma) * See our [security policy](https://github.com/puma/puma/security/policy)

View original source
Open Source Vulnerabilities CVE-2020-11076

In Puma (RubyGem) before 4.3.4 and 3.12.5, an attacker could smuggle an HTTP response, by using an invalid transfer-encoding header. The problem has been fixed in Puma 3.12.5 and Puma 4.3.4.

View original source

05 / REFERENCES

Further evidence