CVE-2021-41136

Severity CVSS v4.0:

Pending analysis

Type:

Unavailable / Other

Publication date:

12/10/2021

Last modified:

27/05/2025

Description

Puma is a HTTP 1.1 server for Ruby/Rack applications. Prior to versions 5.5.1 and 4.3.9, using `puma` with a proxy which forwards HTTP header values which contain the LF character could allow HTTP request smugggling. A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client. The only proxy which has this behavior, as far as the Puma team is aware of, is Apache Traffic Server. If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request&#39;s body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client. This vulnerability was patched in Puma 5.5.1 and 4.3.9. As a workaround, do not use Apache Traffic Server with `puma`.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 3.70 LOW
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): Low
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): Low
Integrity (I): Low
Availability (A): None

Base Score 3.x

3.70

Severity 3.x

LOW

Vector 2.0

AV:N/AC:H/Au:S/C:P/I:P/A:N CVSS v2.0 Severity and Metrics:

Base Score: 3.60 LOW
Vector: AV:N/AC:H/Au:S/C:P/I:P/A:N

Attack Vector (AV): Network
Attack Complexity (AC): High
Authentication (Au): Single
Confidentiality (C): Physical
Integrity (I): Physical
Availability (A): None

Base Score 2.0

3.60

Severity 2.0

LOW

Vulnerable products and versions

CPE	From	Up to
cpe:2.3:a:puma:puma::::::ruby::*		4.3.8 (including)
cpe:2.3:a:puma:puma::::::ruby::*	5.0.0 (including)	5.5.0 (including)
cpe:2.3:o:debian:debian_linux:10.0:::::::*
cpe:2.3:o:debian:debian_linux:11.0:::::::*

To consult the complete list of CPE names with products and versions, see this page

CVE-2021-41136

Description

Impact

Vulnerable products and versions

References to Advisories, Solutions, and Tools