GHSA-q28m-8xjw-8vr5
Vulnerability from github
Published
2021-05-18 01:27
Modified
2023-05-16 16:19
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Puma's Keepalive Connections Causing Denial Of Service
Details

This vulnerability is related to CVE-2019-16770.

Impact

The fix for CVE-2019-16770 was incomplete. The original fix only protected existing connections that had already been accepted from having their requests starved by greedy persistent-connections saturating all threads in the same process. However, new connections may still be starved by greedy persistent-connections saturating all threads in all processes in the cluster.

A puma server which received more concurrent keep-alive connections than the server had threads in its threadpool would service only a subset of connections, denying service to the unserved connections.

Patches

This problem has been fixed in puma 4.3.8 and 5.3.1.

Workarounds

Setting queue_requests false also fixes the issue. This is not advised when using puma without a reverse proxy, such as nginx or apache, because you will open yourself to slow client attacks (e.g. slowloris).

The fix is very small. A git patch is available here for those using unsupported versions of Puma.

For more information

If you have any questions or comments about this advisory:

Acknowledgements

Thank you to @MSP-Greg, @wjordan and @evanphx for their review on this issue.

Thank you to @ioquatix for providing a modified fork of wrk which made debugging this issue much easier.

Show details on source website

To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.3.7"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "puma"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.3.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.3.0"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "puma"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0"
            },
            {
              "fixed": "5.3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-29509"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-05-18T01:26:55Z",
    "nvd_published_at": "2021-05-11T17:15:00Z",
    "severity": "HIGH"
  },
  "details": "This vulnerability is related to [CVE-2019-16770](https://github.com/puma/puma/security/advisories/GHSA-7xx3-m584-x994).\n\n### Impact\n\nThe fix for CVE-2019-16770 was incomplete. The original fix only protected existing connections that had already been accepted from having their requests starved by greedy persistent-connections saturating all threads in the same process. However, new connections may still be starved by greedy persistent-connections saturating all threads in all processes in the cluster.\n\nA `puma` server which received more concurrent `keep-alive` connections than the server had threads in its threadpool would service only a subset of connections, denying service to the unserved connections.\n\n### Patches\n\nThis problem has been fixed in `puma` 4.3.8 and 5.3.1.\n\n### Workarounds\n\nSetting `queue_requests false` also fixes the issue. This is not advised when using `puma` without a reverse proxy, such as `nginx` or `apache`, because you will open yourself to slow client attacks (e.g. [slowloris](https://en.wikipedia.org/wiki/Slowloris_(computer_security))).\n\nThe fix is very small. [A git patch is available here](https://gist.github.com/nateberkopec/4b3ea5676c0d70cbb37c82d54be25837) for those using [unsupported versions](https://github.com/puma/puma/security/policy#supported-versions) of Puma.\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* To report problems with this fix or to report another vulnerability, see [our security policy.](https://github.com/puma/puma/security/policy)\n\n### Acknowledgements\n\nThank you to @MSP-Greg, @wjordan and @evanphx for their review on this issue. \n\nThank you to @ioquatix for providing a modified fork of `wrk` which made debugging this issue much easier.",
  "id": "GHSA-q28m-8xjw-8vr5",
  "modified": "2023-05-16T16:19:44Z",
  "published": "2021-05-18T01:27:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/puma/puma/security/advisories/GHSA-q28m-8xjw-8vr5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-29509"
    },
    {
      "type": "WEB",
      "url": "https://gist.github.com/nateberkopec/4b3ea5676c0d70cbb37c82d54be25837"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/puma/puma"
    },
    {
      "type": "WEB",
      "url": "https://github.com/puma/puma/security/policy"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2021-29509.yml"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2022/08/msg00015.html"
    },
    {
      "type": "WEB",
      "url": "https://rubygems.org/gems/puma"
    },
    {
      "type": "WEB",
      "url": "https://security.gentoo.org/glsa/202208-28"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Puma\u0027s Keepalive Connections Causing Denial Of Service"
}


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