3.7 Low
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
3.6 Low
CVSS2
Access Vector
NETWORK
Access Complexity
HIGH
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:H/Au:S/C:P/I:P/A:N
0.002 Low
EPSS
Percentile
64.3%
Prior to puma
version 5.5.0, using puma
with a proxy which forwards LF characters as line endings could allow HTTP request smuggling. A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client.
This behavior (forwarding LF characters as line endings) is very uncommon amongst proxy servers, so we have graded the impact here as “low”. Puma is only aware of a single proxy server which has this behavior.
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.
This vulnerability only affects Puma installations without any proxy in front.
Use a proxy which does not forward LF characters as line endings.
Proxies which do not forward LF characters as line endings:
If you are dealing with legacy clients that want to send LF
as a line ending in an HTTP header, this will cause those clients to receive a 400
error.
If you have any questions or comments about this advisory:
github.com/advisories/GHSA-48w2-rm65-62xx
github.com/puma/puma/commit/acdc3ae571dfae0e045cf09a295280127db65c7f
github.com/puma/puma/releases/tag/v4.3.9
github.com/puma/puma/releases/tag/v5.5.1
github.com/puma/puma/security/advisories/GHSA-48w2-rm65-62xx
github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2021-41136.yml
lists.debian.org/debian-lts-announce/2022/08/msg00015.html
nvd.nist.gov/vuln/detail/CVE-2021-41136
security.gentoo.org/glsa/202208-28
www.debian.org/security/2022/dsa-5146
3.7 Low
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
3.6 Low
CVSS2
Access Vector
NETWORK
Access Complexity
HIGH
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:H/Au:S/C:P/I:P/A:N
0.002 Low
EPSS
Percentile
64.3%