Vulnerability-Lookup

UBUNTU-CVE-2026-49825 (CVE-2026-49825)

Vulnerability from osv_ubuntu – Published: 2026-08-20 15:17 – Updated: 2026-09-02 16:18 – Source website

Details

lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in lxml.html.defs.link_attrs were missing xlink:href, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5.

Severity

8.2 (High)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-49825	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-49825	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python-lxml",
            "binary_version": "3.3.3-1ubuntu0.2+esm5"
          },
          {
            "binary_name": "python3-lxml",
            "binary_version": "3.3.3-1ubuntu0.2+esm5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "lxml",
        "purl": "pkg:deb/ubuntu/lxml@3.3.3-1ubuntu0.2+esm5?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.2.0-1",
        "3.3.0~beta2-1",
        "3.3.0~beta4-1",
        "3.3.1-1",
        "3.3.2-1",
        "3.3.2-1build1",
        "3.3.3-1",
        "3.3.3-1ubuntu0.1",
        "3.3.3-1ubuntu0.2",
        "3.3.3-1ubuntu0.2+esm1",
        "3.3.3-1ubuntu0.2+esm2",
        "3.3.3-1ubuntu0.2+esm3",
        "3.3.3-1ubuntu0.2+esm5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python-lxml",
            "binary_version": "3.5.0-1ubuntu0.4+esm2"
          },
          {
            "binary_name": "python3-lxml",
            "binary_version": "3.5.0-1ubuntu0.4+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "lxml",
        "purl": "pkg:deb/ubuntu/lxml@3.5.0-1ubuntu0.4+esm2?arch=source\u0026distro=esm-infra/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.4.4-1",
        "3.5.0-1",
        "3.5.0-1build1",
        "3.5.0-1ubuntu0.1",
        "3.5.0-1ubuntu0.2",
        "3.5.0-1ubuntu0.3",
        "3.5.0-1ubuntu0.4",
        "3.5.0-1ubuntu0.4+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python-lxml",
            "binary_version": "4.2.1-1ubuntu0.6"
          },
          {
            "binary_name": "python3-lxml",
            "binary_version": "4.2.1-1ubuntu0.6"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "lxml",
        "purl": "pkg:deb/ubuntu/lxml@4.2.1-1ubuntu0.6?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.0.0-1",
        "4.1.0-1",
        "4.2.0-1",
        "4.2.1-1",
        "4.2.1-1ubuntu0.1",
        "4.2.1-1ubuntu0.2",
        "4.2.1-1ubuntu0.3",
        "4.2.1-1ubuntu0.4",
        "4.2.1-1ubuntu0.6"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python-lxml",
            "binary_version": "4.5.0-1ubuntu0.5"
          },
          {
            "binary_name": "python3-lxml",
            "binary_version": "4.5.0-1ubuntu0.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "lxml",
        "purl": "pkg:deb/ubuntu/lxml@4.5.0-1ubuntu0.5?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.4.1-1",
        "4.4.1-1build1",
        "4.4.2-1",
        "4.5.0-1",
        "4.5.0-1ubuntu0.1",
        "4.5.0-1ubuntu0.2",
        "4.5.0-1ubuntu0.3",
        "4.5.0-1ubuntu0.5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-lxml",
            "binary_version": "4.8.0-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "lxml",
        "purl": "pkg:deb/ubuntu/lxml@4.8.0-1build1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.6.3+dfsg-0.1",
        "4.6.4-1",
        "4.6.4-1ubuntu1",
        "4.7.1-1",
        "4.8.0-1",
        "4.8.0-1build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-lxml",
            "binary_version": "5.2.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "lxml",
        "purl": "pkg:deb/ubuntu/lxml@5.2.1-1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.9.3-1",
        "4.9.3-1build1",
        "4.9.4-1",
        "5.1.0-1",
        "5.1.0-1build1",
        "5.1.0-1build2",
        "5.2.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-lxml",
            "binary_version": "6.0.2-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "lxml",
        "purl": "pkg:deb/ubuntu/lxml@6.0.2-1build1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "6.0.1-1",
        "6.0.1-1build1",
        "6.0.2-1",
        "6.0.2-1build1"
      ]
    }
  ],
  "aliases": [],
  "details": "lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in ``lxml.html.defs.link_attrs`` were missing ``xlink:href``, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5.",
  "id": "UBUNTU-CVE-2026-49825",
  "modified": "2026-09-02T16:18:22Z",
  "published": "2026-08-20T15:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-49825"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-49825"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-49825"
  ]
}

CVE-2026-49825 (GCVE-0-2026-49825)

Vulnerability from cvelistv5 – Published: 2026-08-20 14:42 – Updated: 2026-08-21 16:41

Title

lxml: javascript: URL bypass in Cleaner via xlink:href

Summary

lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in ``lxml.html.defs.link_attrs`` were missing ``xlink:href``, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5.

Severity

8.2 (High)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-21 16:41 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-184 - Incomplete List of Disallowed Inputs

Assigner

GitHub_M mitre root

References

5 references

URL	Tags
https://github.com/fedora-python/lxml_html_clean/…	x_refsource_CONFIRM
https://github.com/fedora-python/lxml_html_clean/…	x_refsource_MISC
https://github.com/lxml/lxml/commit/5927a6d5e8518…	x_refsource_MISC
https://github.com/fedora-python/lxml_html_clean/…	x_refsource_MISC
https://github.com/lxml/lxml/releases/tag/lxml-6.1.1	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
lxml	lxml	Affected: < 6.1.1
fedora-python	lxml_html_clean	Affected: < 0.4.5

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-49825",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-21T16:41:32.043801Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-21T16:41:54.849Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/fedora-python/lxml_html_clean/security/advisories/GHSA-4jhm-jv67-739f"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "lxml",
          "vendor": "lxml",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.1.1"
            }
          ]
        },
        {
          "product": "lxml_html_clean",
          "vendor": "fedora-python",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.4.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in ``lxml.html.defs.link_attrs`` were missing ``xlink:href``, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-184",
              "description": "CWE-184: Incomplete List of Disallowed Inputs",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-20T14:42:30.748Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/fedora-python/lxml_html_clean/security/advisories/GHSA-4jhm-jv67-739f",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/fedora-python/lxml_html_clean/security/advisories/GHSA-4jhm-jv67-739f"
        },
        {
          "name": "https://github.com/fedora-python/lxml_html_clean/commit/322357ac61c6cf80fcbaba53b4e92e31f3ded9f2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/fedora-python/lxml_html_clean/commit/322357ac61c6cf80fcbaba53b4e92e31f3ded9f2"
        },
        {
          "name": "https://github.com/lxml/lxml/commit/5927a6d5e851845140975d99b65461e255caaab0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/lxml/lxml/commit/5927a6d5e851845140975d99b65461e255caaab0"
        },
        {
          "name": "https://github.com/fedora-python/lxml_html_clean/releases/tag/0.4.5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/fedora-python/lxml_html_clean/releases/tag/0.4.5"
        },
        {
          "name": "https://github.com/lxml/lxml/releases/tag/lxml-6.1.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/lxml/lxml/releases/tag/lxml-6.1.1"
        }
      ],
      "source": {
        "advisory": "GHSA-4jhm-jv67-739f",
        "discovery": "UNKNOWN"
      },
      "title": "lxml: javascript: URL bypass in Cleaner via xlink:href"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-49825",
    "datePublished": "2026-08-20T14:42:30.748Z",
    "dateReserved": "2026-06-01T18:50:36.055Z",
    "dateUpdated": "2026-08-21T16:41:54.849Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.