CVE-2021-41136

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'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`.

CvssV3 impact

Version

3.1

VectorString

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

AttackVector

NETWORK

AttackComplexity

LOW

PrivilegesRequired

LOW

UserInteraction

REQUIRED

Scope

UNCHANGED

ConfidentialityImpact

LOW

IntegrityImpact

LOW

AvailabilityImpact

NONE

BaseScore

4.6

BaseSeverity

MEDIUM

CvssV2 impact

AccessComplexity

MEDIUM

ConfidentialityImpact

PARTIAL

AvailabilityImpact

NONE

IntegrityImpact

PARTIAL

BaseScore

4.9

VectorString

AV:N/AC:M/Au:S/C:P/I:P/A:N

Version

2.0

AccessVector

NETWORK

Authentication

SINGLE