GHSA-3X8C-FMPC-5RMQ

Vulnerability from github – Published: 2020-10-16 16:56 – Updated: 2024-09-24 17:41
VLAI?
Summary
Cross-site scripting (XSS) vulnerability in the fallback authentication endpoint
Details

Impact

The fallback authentication endpoint served via Synapse was vulnerable to cross-site scripting (XSS) attacks. The impact depends on the configuration of the domain that Synapse is deployed on, but may allow access to cookies and other browser data, CSRF vulnerabilities, and access to other resources served on the same domain or parent domains.

Patches

This is fixed by #8444, which is included in Synapse v1.21.0.

Workarounds

If the homeserver is not configured to use reCAPTCHA, consent (terms of service), or single sign-on then the affected endpoint can be blocked at a reverse proxy:

  • /_matrix/client/r0/auth/.*/fallback/web
  • /_matrix/client/unstable/auth/.*/fallback/web
Severity ?
6.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.1 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "matrix-synapse"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.21.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2020-26891"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2020-10-16T16:55:42Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Impact\nThe fallback authentication endpoint served via Synapse was vulnerable to cross-site scripting (XSS) attacks. The impact depends on the configuration of the domain that Synapse is deployed on, but may allow access to cookies and other browser data, CSRF vulnerabilities, and access to other resources served on the same domain or parent domains.\n\n### Patches\nThis is fixed by #8444, which is included in Synapse v1.21.0.\n\n### Workarounds\nIf the homeserver is not configured to use reCAPTCHA, consent (terms of service), or single sign-on then the affected endpoint can be blocked at a reverse proxy:\n\n* `/_matrix/client/r0/auth/.*/fallback/web`\n* `/_matrix/client/unstable/auth/.*/fallback/web`",
  "id": "GHSA-3x8c-fmpc-5rmq",
  "modified": "2024-09-24T17:41:06Z",
  "published": "2020-10-16T16:56:04Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-26891"
    },
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/pull/8444"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/matrix-org/synapse"
    },
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/releases"
    },
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/releases/tag/v1.21.2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2020-238.yaml"
    },
    {
      "type": "WEB",
      "url": "https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisory"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Cross-site scripting (XSS) vulnerability in the fallback authentication endpoint"
}


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  • 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.