What’s Vulnerable › Vulnerabilities
CVE-2020-11076: HTTP Smuggling via Transfer-Encoding Header in Puma
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 4.1% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2020-05-22 · updated 2026-06-17
- Weakness: CWE-444
Description
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.
Affected products
- Debian Linux: 9.0
- Fedoraproject Fedora: 33
- puma: from 3.0.0 before 3.12.6; from 4.0.0 before 4.3.5 — fixed in 3.12.6, 4.3.5
- Rubygems Puma: before 3.12.5; from 4.0.0 before 4.3.4; 0.8.0, 0.8.1, 0.8.2, 0.9.0, 0.9.1, 0.9.2 (+110) — fixed in 3.12.5, 4.3.4
How to fix
Upgrade to a fixed version: puma 3.12.6, 4.3.5; Rubygems Puma 3.12.5, 4.3.4. Check the vendor advisory for mitigations.
References
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00034.html
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00038.html
- https://github.com/puma/puma/blob/master/History.md#434435-and-31253126--2020-05-22
- https://github.com/puma/puma/commit/f24d5521295a2152c286abb0a45a1e1e2bd275bd
- https://github.com/puma/puma/security/advisories/GHSA-x7jg-6pwg-fx5h
- https://lists.debian.org/debian-lts-announce/2020/10/msg00009.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SKIY5H67GJIGJL6SMFWFLUQQQR3EMVPR/
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00034.html
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00038.html
- https://github.com/puma/puma/blob/master/History.md#434435-and-31253126--2020-05-22
- https://github.com/puma/puma/commit/f24d5521295a2152c286abb0a45a1e1e2bd275bd
- https://github.com/puma/puma/security/advisories/GHSA-x7jg-6pwg-fx5h
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