CVE-2021-41136
Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') in puma
Public exploit available. Not confirmed exploited in the wild yet. Fixed in 5.5.1.
What to do
Find your product and version, then upgrade to the build on the right.
- PumaAffected: >= 5.0.0, < 5.5.1Upgrade to: not statedAffected: < 4.3.9Upgrade to: not statedStated by: CVE record
- RubyGems pumaAffected: ≥ 5.0.0, < 5.5.1Upgrade to: 5.5.1Stated by: GitHub advisory
- Сообщество свободного программного обеспечения Debian GNU/LinuxAffected: 10Upgrade to: not statedStated by: BDU
- ООО «Ред Софт» РЕД ОСAffected: 7.3Upgrade to: not statedStated by: BDU
- АО «НППКТ» ОСОН ОСнова ОnyxAffected: до 2.6Upgrade to: not statedStated by: BDU
Versions as the sources state them. 1 more product has version data. Full version matrix after sign-in
What it is
From the CVE record
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`.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
1 source with a proof of concept or module.
Exploit links, PoCs and Metasploit modules after sign-in- EPSS
1.2% chance of exploitation activity in the next 30 days, which ranks it in the 68th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
The patch came 283 days before any public exploit.
- OpenVAS check added
- Public exploit / PoCsource: github-poc
- Patch availablerecord updated
- Publishedweakness classified, att&ck mapped
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
Scored 3.7 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
- Privileges Required LowRequires basic user-level privileges
- User Interaction RequiredA user must click a link, open a file, or perform some action
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality LowSome restricted information is disclosed, but limited in scope
- Integrity LowData modification is possible but limited in scope or consequence
- Availability NoneNo availability impact
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
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