Vulnerability-Lookup

ubuntu-cve-2021-33193

Vulnerability from osv_ubuntu

Published

2021-08-16 08:15

Modified

2026-04-22 07:40

Summary

Details

A crafted method sent through HTTP/2 will bypass validation and be forwarded by mod_proxy, which can lead to request splitting or cache poisoning. This issue affects Apache HTTP Server 2.4.17 to 2.4.48.

Severity

7.5 (High)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2021-33193	REPORT
	https://portswigger.net/research/http2	REPORT
	https://ubuntu.com/security/notices/USN-5090-1	ADVISORY
	https://www.cve.org/CVERecord?id=CVE-2021-33193	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "apache2",
            "binary_version": "2.4.29-1ubuntu4.17"
          },
          {
            "binary_name": "apache2-bin",
            "binary_version": "2.4.29-1ubuntu4.17"
          },
          {
            "binary_name": "apache2-data",
            "binary_version": "2.4.29-1ubuntu4.17"
          },
          {
            "binary_name": "apache2-suexec-custom",
            "binary_version": "2.4.29-1ubuntu4.17"
          },
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            "binary_name": "apache2-suexec-pristine",
            "binary_version": "2.4.29-1ubuntu4.17"
          },
          {
            "binary_name": "apache2-utils",
            "binary_version": "2.4.29-1ubuntu4.17"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "apache2",
        "purl": "pkg:deb/ubuntu/apache2@2.4.29-1ubuntu4.17?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
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            }
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        }
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        "2.4.29-1ubuntu2",
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        "2.4.29-1ubuntu4.4",
        "2.4.29-1ubuntu4.5",
        "2.4.29-1ubuntu4.6",
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        "2.4.29-1ubuntu4.8",
        "2.4.29-1ubuntu4.10",
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        "2.4.29-1ubuntu4.12",
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        "2.4.29-1ubuntu4.14",
        "2.4.29-1ubuntu4.16"
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    },
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      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "apache2",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-bin",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-data",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-suexec-custom",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
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          },
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            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "libapache2-mod-proxy-uwsgi",
            "binary_version": "2.4.41-4ubuntu3.5"
          }
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      },
      "package": {
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      },
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        "2.4.41-4ubuntu2",
        "2.4.41-4ubuntu3",
        "2.4.41-4ubuntu3.1",
        "2.4.41-4ubuntu3.3",
        "2.4.41-4ubuntu3.4"
      ]
    }
  ],
  "aliases": [],
  "details": "A crafted method sent through HTTP/2 will bypass validation and be forwarded by mod_proxy, which can lead to request splitting or cache poisoning. This issue affects Apache HTTP Server 2.4.17 to 2.4.48.",
  "id": "UBUNTU-CVE-2021-33193",
  "modified": "2026-04-22T07:40:04Z",
  "published": "2021-08-16T08:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-33193"
    },
    {
      "type": "REPORT",
      "url": "https://portswigger.net/research/http2"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-5090-1"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2021-33193"
    }
  ],
  "related": [
    "USN-5090-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2021-33193"
  ]
}

CVE-2021-33193 (GCVE-0-2021-33193)

Vulnerability from cvelistv5 – Published: 2021-08-16 00:00 – Updated: 2024-08-03 23:42

Title

Request splitting via HTTP/2 method injection and mod_proxy

Summary

Severity

No CVSS data available.

CWE

Request Splitting

Assigner

apache

References

13 references

URL	Tags
https://portswigger.net/research/http2
https://github.com/apache/httpd/commit/ecebcc035c…
https://lists.apache.org/thread.html/re4162adc051…	mailing-list
https://lists.apache.org/thread.html/ree7519d7141…	mailing-list
https://lists.fedoraproject.org/archives/list/pac…	vendor-advisory
https://lists.fedoraproject.org/archives/list/pac…	vendor-advisory
https://tools.cisco.com/security/center/content/C…	vendor-advisory
https://www.oracle.com/security-alerts/cpujan2022.html
https://security.netapp.com/advisory/ntap-2021091…
https://www.tenable.com/security/tns-2021-17
https://www.oracle.com/security-alerts/cpuapr2022.html
https://security.gentoo.org/glsa/202208-20	vendor-advisory
https://lists.debian.org/debian-lts-announce/2023…	mailing-list

Impacted products

1 product

Vendor	Product	Version
Apache Software Foundation	Apache HTTP Server	Affected: Apache HTTP Server 2.4 2.4.17 to 2.4.48

Credits

Reported by James Kettle of PortSwigger

Show details on NVD website

JSON

To clipboard

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usn-5090-1

Vulnerability from osv_ubuntu

Published

2021-09-27 14:06

Modified

2026-04-22 07:37

Summary

apache2 vulnerabilities

Details

James Kettle discovered that the Apache HTTP Server HTTP/2 module incorrectly handled certain crafted methods. A remote attacker could possibly use this issue to perform request splitting or cache poisoning attacks. (CVE-2021-33193)

It was discovered that the Apache HTTP Server incorrectly handled certain malformed requests. A remote attacker could possibly use this issue to cause the server to crash, resulting in a denial of service. (CVE-2021-34798)

Li Zhi Xin discovered that the Apache mod_proxy_uwsgi module incorrectly handled certain request uri-paths. A remote attacker could possibly use this issue to cause the server to crash, resulting in a denial of service. This issue only affected Ubuntu 20.04 LTS and Ubuntu 21.04. (CVE-2021-36160)

It was discovered that the Apache HTTP Server incorrectly handled escaping quotes. If the server was configured with third-party modules, a remote attacker could use this issue to cause the server to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2021-39275)

It was discovered that the Apache mod_proxy module incorrectly handled certain request uri-paths. A remote attacker could possibly use this issue to cause the server to forward requests to arbitrary origin servers. (CVE-2021-40438)

References

URL

Type

	https://ubuntu.com/security/notices/USN-5090-1	ADVISORY
	https://ubuntu.com/security/CVE-2021-33193	REPORT
	https://ubuntu.com/security/CVE-2021-34798	REPORT
	https://ubuntu.com/security/CVE-2021-36160	REPORT
	https://ubuntu.com/security/CVE-2021-39275	REPORT
	https://ubuntu.com/security/CVE-2021-40438	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2021-33193",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
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              ]
            },
            {
              "id": "CVE-2021-34798",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            },
            {
              "id": "CVE-2021-39275",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                  "type": "CVSS_V3"
                },
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                  "score": "medium",
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      },
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      "versions": [
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        "2.4.29-1ubuntu4",
        "2.4.29-1ubuntu4.1",
        "2.4.29-1ubuntu4.2",
        "2.4.29-1ubuntu4.3",
        "2.4.29-1ubuntu4.4",
        "2.4.29-1ubuntu4.5",
        "2.4.29-1ubuntu4.6",
        "2.4.29-1ubuntu4.7",
        "2.4.29-1ubuntu4.8",
        "2.4.29-1ubuntu4.10",
        "2.4.29-1ubuntu4.11",
        "2.4.29-1ubuntu4.12",
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      ]
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                  "type": "CVSS_V3"
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                  "type": "Ubuntu"
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              "id": "CVE-2021-34798",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
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                }
              ]
            },
            {
              "id": "CVE-2021-36160",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            },
            {
              "id": "CVE-2021-39275",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:20.04:LTS"
        }
      },
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "apache2",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-bin",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-data",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-suexec-custom",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-suexec-pristine",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "apache2-utils",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "libapache2-mod-md",
            "binary_version": "2.4.41-4ubuntu3.5"
          },
          {
            "binary_name": "libapache2-mod-proxy-uwsgi",
            "binary_version": "2.4.41-4ubuntu3.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "apache2",
        "purl": "pkg:deb/ubuntu/apache2@2.4.41-4ubuntu3.5?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.4.41-4ubuntu3.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.4.41-1ubuntu1",
        "2.4.41-4ubuntu1",
        "2.4.41-4ubuntu2",
        "2.4.41-4ubuntu3",
        "2.4.41-4ubuntu3.1",
        "2.4.41-4ubuntu3.3",
        "2.4.41-4ubuntu3.4"
      ]
    }
  ],
  "aliases": [],
  "details": "James Kettle discovered that the Apache HTTP Server HTTP/2 module\nincorrectly handled certain crafted methods. A remote attacker could\npossibly use this issue to perform request splitting or cache poisoning\nattacks. (CVE-2021-33193)\n\nIt was discovered that the Apache HTTP Server incorrectly handled certain\nmalformed requests. A remote attacker could possibly use this issue to\ncause the server to crash, resulting in a denial of service.\n(CVE-2021-34798)\n\nLi Zhi Xin discovered that the Apache mod_proxy_uwsgi module incorrectly\nhandled certain request uri-paths. A remote attacker could possibly use\nthis issue to cause the server to crash, resulting in a denial of service.\nThis issue only affected Ubuntu 20.04 LTS and Ubuntu 21.04.\n(CVE-2021-36160)\n\nIt was discovered that the Apache HTTP Server incorrectly handled escaping\nquotes. If the server was configured with third-party modules, a remote\nattacker could use this issue to cause the server to crash, resulting in a\ndenial of service, or possibly execute arbitrary code. (CVE-2021-39275)\n\nIt was discovered that the Apache mod_proxy module incorrectly handled\ncertain request uri-paths. A remote attacker could possibly use this issue\nto cause the server to forward requests to arbitrary origin servers.\n(CVE-2021-40438)\n",
  "id": "USN-5090-1",
  "modified": "2026-04-22T07:37:00Z",
  "published": "2021-09-27T14:06:45Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-5090-1"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-33193"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-34798"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-36160"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-39275"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-40438"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "summary": "apache2 vulnerabilities",
  "upstream": [
    "UBUNTU-CVE-2021-33193",
    "UBUNTU-CVE-2021-34798",
    "UBUNTU-CVE-2021-36160",
    "UBUNTU-CVE-2021-39275",
    "UBUNTU-CVE-2021-40438"
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

ubuntu-cve-2021-33193

Vulnerability from osv_ubuntu

CVE-2021-33193 (GCVE-0-2021-33193)

usn-5090-1

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature