CVE-2020-11076: Puma HTTP Smuggling Vulnerability

HIGH
Advisory Identifier: GHSA-x7jg-6pwg-fx5h
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CVSS 7.5
CWE-444
Published
Advisory Summary

CVE-2020-11076 is a HIGH (CVSS 7.5) http smuggling vulnerability (CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')) affecting Puma libraries in the RubyGems ecosystem. The issue involves http smuggling via transfer-encoding header in puma. Remediation is available by upgrading affected packages to version 3.12.5, 4.3.4.

CVE-2020-11076 at a Glance

CVE Identifier CVE-2020-11076
GHSA Identifier GHSA-x7jg-6pwg-fx5h
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected Product Puma
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2020-11076

To remediate this vulnerability, upgrade all affected Puma dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

puma fixed: 3.12.5 
Upgrade puma to 3.12.5
puma fixed: 4.3.4 
Upgrade puma to 4.3.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for puma

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-11076, inspect your project dependencies for Puma:

inspect dependencies for puma

Analyze the terminal output to locate any version of Puma in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.12.5), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'), where 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. In Puma, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact By using an invalid transfer-encoding header, an attacker could [smuggle an HTTP response.](https://portswigger.net/web-security/request-smuggling) Originally reported by @ZeddYu, who has our thanks for the detailed report. ### Patches The problem has been fixed in Puma 3.12.5 and Puma 4.3.4. ### For more information If you have any questions or comments about this advisory: * Open an issue in [Puma](https://github.com/puma/puma) * See our [security policy](https://github.com/puma/puma/security/policy)

CVE-2020-11076 Affected Puma Versions

2 component(s)
Fixed Versions:
3.12.54.3.4
Product / Package Ecosystem Affected Versions Fixed Version
puma
gem/puma
RubyGems
< 3.12.5
3.12.5
puma
gem/puma
RubyGems
≥ 4.0.0
< 4.3.4
4.3.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/puma/puma/security/advisories/GHSA-x7jg-6pwg-fx5h
NVD — CVE-2020-11076 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-11076
Security Fix Commit FIX COMMIT
https://github.com/puma/puma/commit/f24d5521295a2152c286abb0a45a1e1e2bd275bd
Puma Source Repository REPOSITORY
https://github.com/puma/puma
Puma Source Repository REPOSITORY
https://github.com/puma/puma/blob/master/History.md#434435-and-31253126--2020-05-22
Puma Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2020-11076.yml
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2020/10/msg00009.html
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SKIY5H67GJIGJL6SMFWFLUQQQR3EMVPR
Puma Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00034.html
Puma Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00038.html

Frequently Asked Questions

What is CVE-2020-11076?
CVE-2020-11076 is a security vulnerability in Puma involving HTTP Smuggling via Transfer-Encoding Header in Puma under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling').
Which Puma versions are affected?
Affected versions include releases prior to 3.12.5, 4.3.4 across affected packages: puma.
What version fixes CVE-2020-11076?
Upgrading to 3.12.5, 4.3.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is puma affected?
Yes, puma is affected in releases prior to 3.12.5, 4.3.4. Upgrade your dependency to 3.12.5, 4.3.4 or later.
What is the CVSS score of CVE-2020-11076?
CVE-2020-11076 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2020-11076?
CVE-2020-11076 is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') (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.).
How can I check RubyGems dependencies for CVE-2020-11076?
Run the dependency tree command: 'inspect dependencies for puma'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-x7jg-6pwg-fx5h",
  "modified" : "2023-05-16T15:53:31Z",
  "published" : "2020-05-22T14:55:05Z",
  "aliases" : [ "CVE-2020-11076" ],
  "summary" : "HTTP Smuggling via Transfer-Encoding Header in Puma",
  "details" : "### Impact\n\nBy using an invalid transfer-encoding header, an attacker could [smuggle an HTTP response.](https://portswigger.net/web-security/request-smuggling)\n\nOriginally reported by @ZeddYu, who has our thanks for the detailed report.\n\n### Patches\n\nThe problem has been fixed in Puma 3.12.5 and Puma 4.3.4.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n* Open an issue in [Puma](https://github.com/puma/puma)\n* See our [security policy](https://github.com/puma/puma/security/policy)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "puma"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.12.5"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "puma"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.3.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/puma/puma/security/advisories/GHSA-x7jg-6pwg-fx5h"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-11076"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/puma/puma/commit/f24d5521295a2152c286abb0a45a1e1e2bd275bd"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/puma/puma"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/puma/puma/blob/master/History.md#434435-and-31253126--2020-05-22"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2020-11076.yml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2020/10/msg00009.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SKIY5H67GJIGJL6SMFWFLUQQQR3EMVPR"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00034.html"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00038.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-444" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-05-22T14:40:36Z",
    "nvd_published_at" : "2020-05-22T15:15:00Z"
  }
}