ubuntu-cve-2021-40823
Vulnerability from osv_ubuntu
Published
2021-09-13 19:15
Modified
2025-10-24 04:50
Summary
Details

A logic error in the room key sharing functionality of matrix-js-sdk (aka Matrix Javascript SDK) before 12.4.1 allows a malicious Matrix homeserver present in an encrypted room to steal room encryption keys (via crafted Matrix protocol messages) that were originally sent by affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.

Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libjs-matrix-js-sdk",
            "binary_version": "0.9.2-1"
          },
          {
            "binary_name": "node-matrix-js-sdk",
            "binary_version": "0.9.2-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "node-matrix-js-sdk",
        "purl": "pkg:deb/ubuntu/node-matrix-js-sdk@0.9.2-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.9.2-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libjs-matrix-js-sdk",
            "binary_version": "9.11.0+~cs9.9.16-1"
          },
          {
            "binary_name": "node-matrix-js-sdk",
            "binary_version": "9.11.0+~cs9.9.16-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "node-matrix-js-sdk",
        "purl": "pkg:deb/ubuntu/node-matrix-js-sdk@9.11.0+~cs9.9.16-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "9.3.0+~cs9.9.16-2",
        "9.11.0+~cs9.9.16-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libjs-matrix-js-sdk",
            "binary_version": "9.11.0+~cs9.9.16-2"
          },
          {
            "binary_name": "node-matrix-js-sdk",
            "binary_version": "9.11.0+~cs9.9.16-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "node-matrix-js-sdk",
        "purl": "pkg:deb/ubuntu/node-matrix-js-sdk@9.11.0+~cs9.9.16-2?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "9.11.0+~cs9.9.16-2"
      ]
    }
  ],
  "aliases": [],
  "details": "A logic error in the room key sharing functionality of matrix-js-sdk (aka Matrix Javascript SDK) before 12.4.1 allows a malicious Matrix homeserver present in an encrypted room to steal room encryption keys (via crafted Matrix protocol messages) that were originally sent by affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.",
  "id": "UBUNTU-CVE-2021-40823",
  "modified": "2025-10-24T04:50:34Z",
  "published": "2021-09-13T19:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-40823"
    },
    {
      "type": "REPORT",
      "url": "https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing/"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/matrix-org/matrix-js-sdk/commit/894c24880da0e1cc81818f51c0db80e3c9fb2be9"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/matrix-org/matrix-js-sdk/releases/tag/v12.4.1"
    },
    {
      "type": "REPORT",
      "url": "https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2021-40823"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2021-40823"
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.