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GeekWala

CVE-2020-11076

HIGH

HTTP Smuggling via Transfer-Encoding Header in Puma

Published May 22, 2020Updated March 13, 2026Source: osv

Summary

### 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)

Remediation

Upgrade to the fixed version using your package manager.

Bundler
Update puma to 3.12.5 or later
gem install puma -v 3.12.5
Bundler
Update puma to 4.3.4 or later
gem install puma -v 4.3.4

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (2)

PackageEcosystemAffectedFixed In
puma
rubygems
0.8.0, 0.8.1, 0.8.2, 0.9.0 (+103 more)3.12.5
puma
rubygems
4.0.0, 4.0.1, 4.1.0, 4.1.1 (+5 more)4.3.4

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 7.5 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Frequently Asked Questions

What is CVE-2020-11076?
HTTP Smuggling via Transfer-Encoding Header in Puma This vulnerability has been assigned a severity rating of HIGH (CVSS score: 7.5/10).
How do I check if my project is affected by CVE-2020-11076?
CVE-2020-11076 affects puma. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2020-11076 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
7.5

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-x7jg-6pwg-fx5h

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