Vulnerability-Lookup

alsa-2021:4158

Vulnerability from osv_almalinux

Published

2021-11-09 08:26

Modified

2021-11-12 10:20

Summary

Moderate: python-lxml security update

Details

lxml is an XML processing library providing access to libxml2 and libxslt libraries using the Python ElementTree API.

Security Fix(es):

python-lxml: Missing input sanitization for formaction HTML5 attributes may lead to XSS (CVE-2021-28957)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "python3-lxml"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.2.3-3.el8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "lxml is an XML processing library providing access to libxml2 and libxslt libraries using the Python ElementTree API. \n\nSecurity Fix(es):\n\n* python-lxml: Missing input sanitization for formaction HTML5 attributes may lead to XSS (CVE-2021-28957)\n\nFor more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.\n\nAdditional Changes:\n\nFor detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.",
  "id": "ALSA-2021:4158",
  "modified": "2021-11-12T10:20:56Z",
  "published": "2021-11-09T08:26:20Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://vulners.com/cve/CVE-2021-28957"
    }
  ],
  "related": [
    "CVE-2021-28957"
  ],
  "summary": "Moderate: python-lxml security update"
}

CVE-2021-28957 (GCVE-0-2021-28957)

Vulnerability from cvelistv5 – Published: 2021-03-21 04:39 – Updated: 2025-12-17 21:31

Summary

An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3.

Severity ?

6.1 (Medium)


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

CWE

Assigner

mitre

References

URL

Tags

	https://bugs.launchpad.net/lxml/+bug/1888153	x_refsource_MISC
	https://github.com/lxml/lxml/pull/316/commits/10e…	x_refsource_MISC
	https://lists.debian.org/debian-lts-announce/2021…	mailing-listx_refsource_MLIST
	https://www.debian.org/security/2021/dsa-4880	vendor-advisoryx_refsource_DEBIAN
	https://lists.fedoraproject.org/archives/list/pac…	vendor-advisoryx_refsource_FEDORA
	https://lists.fedoraproject.org/archives/list/pac…	vendor-advisoryx_refsource_FEDORA
	https://www.oracle.com/security-alerts/cpuoct2021.html	x_refsource_MISC
	https://github.com/lxml/lxml/commit/a5f9cb52079dc…	x_refsource_MISC
	https://security.netapp.com/advisory/ntap-2021052…	x_refsource_CONFIRM
	https://security.gentoo.org/glsa/202208-06	vendor-advisoryx_refsource_GENTOO

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T21:55:12.376Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://bugs.launchpad.net/lxml/+bug/1888153"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270"
          },
          {
            "name": "[debian-lts-announce] 20210324 [SECURITY] [DLA 2606-1] lxml security update",
            "tags": [
              "mailing-list",
              "x_refsource_MLIST",
              "x_transferred"
            ],
            "url": "https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html"
          },
          {
            "name": "DSA-4880",
            "tags": [
              "vendor-advisory",
              "x_refsource_DEBIAN",
              "x_transferred"
            ],
            "url": "https://www.debian.org/security/2021/dsa-4880"
          },
          {
            "name": "FEDORA-2021-28723f9670",
            "tags": [
              "vendor-advisory",
              "x_refsource_FEDORA",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/"
          },
          {
            "name": "FEDORA-2021-4cdb0f68c7",
            "tags": [
              "vendor-advisory",
              "x_refsource_FEDORA",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://security.netapp.com/advisory/ntap-20210521-0004/"
          },
          {
            "name": "GLSA-202208-06",
            "tags": [
              "vendor-advisory",
              "x_refsource_GENTOO",
              "x_transferred"
            ],
            "url": "https://security.gentoo.org/glsa/202208-06"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 6.1,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "LOW",
              "integrityImpact": "LOW",
              "privilegesRequired": "NONE",
              "scope": "CHANGED",
              "userInteraction": "REQUIRED",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2021-28957",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-12-17T21:31:40.372887Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-79",
                "description": "CWE-79 Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-12-17T21:31:43.446Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "An XSS vulnerability was discovered in python-lxml\u0027s clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "n/a",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2022-08-10T05:06:44.000Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://bugs.launchpad.net/lxml/+bug/1888153"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270"
        },
        {
          "name": "[debian-lts-announce] 20210324 [SECURITY] [DLA 2606-1] lxml security update",
          "tags": [
            "mailing-list",
            "x_refsource_MLIST"
          ],
          "url": "https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html"
        },
        {
          "name": "DSA-4880",
          "tags": [
            "vendor-advisory",
            "x_refsource_DEBIAN"
          ],
          "url": "https://www.debian.org/security/2021/dsa-4880"
        },
        {
          "name": "FEDORA-2021-28723f9670",
          "tags": [
            "vendor-advisory",
            "x_refsource_FEDORA"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/"
        },
        {
          "name": "FEDORA-2021-4cdb0f68c7",
          "tags": [
            "vendor-advisory",
            "x_refsource_FEDORA"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999"
        },
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://security.netapp.com/advisory/ntap-20210521-0004/"
        },
        {
          "name": "GLSA-202208-06",
          "tags": [
            "vendor-advisory",
            "x_refsource_GENTOO"
          ],
          "url": "https://security.gentoo.org/glsa/202208-06"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "cve@mitre.org",
          "ID": "CVE-2021-28957",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "n/a",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "n/a"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "n/a"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "An XSS vulnerability was discovered in python-lxml\u0027s clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3."
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "n/a"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://bugs.launchpad.net/lxml/+bug/1888153",
              "refsource": "MISC",
              "url": "https://bugs.launchpad.net/lxml/+bug/1888153"
            },
            {
              "name": "https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270",
              "refsource": "MISC",
              "url": "https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270"
            },
            {
              "name": "[debian-lts-announce] 20210324 [SECURITY] [DLA 2606-1] lxml security update",
              "refsource": "MLIST",
              "url": "https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html"
            },
            {
              "name": "DSA-4880",
              "refsource": "DEBIAN",
              "url": "https://www.debian.org/security/2021/dsa-4880"
            },
            {
              "name": "FEDORA-2021-28723f9670",
              "refsource": "FEDORA",
              "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/"
            },
            {
              "name": "FEDORA-2021-4cdb0f68c7",
              "refsource": "FEDORA",
              "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/"
            },
            {
              "name": "https://www.oracle.com/security-alerts/cpuoct2021.html",
              "refsource": "MISC",
              "url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
            },
            {
              "name": "https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999",
              "refsource": "MISC",
              "url": "https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999"
            },
            {
              "name": "https://security.netapp.com/advisory/ntap-20210521-0004/",
              "refsource": "CONFIRM",
              "url": "https://security.netapp.com/advisory/ntap-20210521-0004/"
            },
            {
              "name": "GLSA-202208-06",
              "refsource": "GENTOO",
              "url": "https://security.gentoo.org/glsa/202208-06"
            }
          ]
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
    "assignerShortName": "mitre",
    "cveId": "CVE-2021-28957",
    "datePublished": "2021-03-21T04:39:35.000Z",
    "dateReserved": "2021-03-21T00:00:00.000Z",
    "dateUpdated": "2025-12-17T21:31:43.446Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

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