Vulnerability · Published Oct 12, 2021 · Assigned by GitHub_M
CVE-2021-41136Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') in puma
Low 3.7
In plain English
A low-severity security flaw in puma from puma. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 68% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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`.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | puma | 5.5.2-1 | DEBIAN-CVE-2021-41136 |
| Debian:13 | puma | 5.5.2-1 | DEBIAN-CVE-2021-41136 |
| Debian:14 | puma | 5.5.2-1 | DEBIAN-CVE-2021-41136 |
| Rocky Linux:8 | libdb | 0:5.3.28-42.el8_4 | RLSA-2022:5498 |
| RubyGems | puma | 5.5.1 | GHSA-48w2-rm65-62xx |
| RubyGems | puma | 4.3.9 | GHSA-48w2-rm65-62xx |
| Ubuntu:22.04:LTS | puma | 5.5.2-2ubuntu2 | UBUNTU-CVE-2021-41136 |
Affected products (as reported)
Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
References
- https://github.com/puma/puma/security/advisories/GHSA-48w2-rm65-62xx x_refsource_CONFIRM
- https://github.com/puma/puma/commit/436c71807f00e07070902a03f79fd3e130eb6b18 x_refsource_MISC
- https://github.com/puma/puma/commit/acdc3ae571dfae0e045cf09a295280127db65c7f x_refsource_MISC
- https://github.com/puma/puma/commit/fb6ad8f8013ab5cdbb2f444cbfabd0b4fde71139 x_refsource_MISC
- DSA-5146 vendor-advisory, x_refsource_DEBIAN, x_transferred
- GLSA-202208-28 vendor-advisory, x_refsource_GENTOO, x_transferred
- [debian-lts-announce] 20220827 [SECURITY] [DLA 3083-1] puma security update mailing-list, x_refsource_MLIST, x_transferred