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`.
Published 2021-10-12 16:15:08
Updated 2022-10-12 13:30:51
Source GitHub, Inc.
View at NVD,   CVE.org

Exploit prediction scoring system (EPSS) score for CVE-2021-41136

Probability of exploitation activity in the next 30 days: 0.25%

Percentile, the proportion of vulnerabilities that are scored at or less: ~ 63 % EPSS Score History EPSS FAQ

CVSS scores for CVE-2021-41136

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source
3.6
LOW AV:N/AC:H/Au:S/C:P/I:P/A:N
3.9
4.9
NIST
3.7
LOW CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
1.2
2.5
NIST
3.7
LOW CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
1.2
2.5
GitHub, Inc.

CWE ids for CVE-2021-41136

  • The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
    Assigned by: security-advisories@github.com (Primary)

References for CVE-2021-41136

Products affected by CVE-2021-41136

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