{
"id": "GHSA-w9fg-xffh-p362",
"aliases": [
"CVE-2021-21394"
],
"details": "### Impact\nMissing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion.\n\n### Patches\nThe issue is fixed by #9321.\n\n### Workarounds\nDepending on the needs and configuration of the homeserver a few options are available:\n\n1. Using email as third-party identifiers be disabled by not configuring the `email` setting.\n2. Using phone numbers as third-party identifiers can be disabled by ensuring that `account_threepid_delegates.msisdn` is not configured.\n3. Additionally, the affected endpoint patterns can be blocked at a reverse proxy:\n\n * `^/_matrix/client/(r0|unstable)/register/email`\n * `^/_matrix/client/(r0|unstable)/register/msisdn`\n * `^/_matrix/client/(r0|unstable)/account/password`\n * `^/_matrix/client/(r0|unstable)/account/3pid`",
"summary": "Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints",
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.28.0"
}
]
}
],
"package": {
"name": "matrix-synapse",
"ecosystem": "PyPI"
}
}
],
"modified": "2024-09-24T20:08:23Z",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
}
],
"published": "2021-04-13T15:12:51Z",
"references": [
{
"url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-w9fg-xffh-p362",
"type": "WEB"
},
{
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21394",
"type": "ADVISORY"
},
{
"url": "https://github.com/matrix-org/synapse/pull/9321",
"type": "WEB"
},
{
"url": "https://github.com/matrix-org/synapse/pull/9393",
"type": "WEB"
},
{
"url": "https://github.com/matrix-org/synapse",
"type": "PACKAGE"
},
{
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2021-27.yaml",
"type": "WEB"
},
{
"url": "https://lists.fedoraproject.org/archives/list/[email protected] /message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY",
"type": "WEB"
},
{
"url": "https://pypi.org/project/matrix-synapse",
"type": "WEB"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-20"
],
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": "2021-04-12T21:15:00Z",
"github_reviewed_at": "2021-04-12T21:01:40Z"
}
}