CVE-2020-11076
HighPublished
HTTP Smuggling via Transfer-Encoding Header in Puma
- Published
- May 22, 2020
- Updated
- Aug 4, 2024
- Assigning CNA
- GitHub_M
- Evidence observed
- Aug 8, 2026
Primary CVSS
7.5/ 10High
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N4.1%
Low · next 30 days
- Percentile
- 90.3%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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.
Sources
1- cougarPoC
Puma, CVE-2020-11076 and CVE-2020-11077
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