CVE-2020-26257: Matrix synapse Denial of Service Vulnerability
HIGHCVE-2020-26257 is a HIGH (CVSS 6.5) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Matrix synapse libraries in the PyPI ecosystem. The issue involves denial of service attack via incorrect parameters in matrix synapse. Remediation is available by upgrading affected packages to version 1.23.1.
CVE-2020-26257 at a Glance
Security Impact
CVSS: 6.5
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
How to Fix CVE-2020-26257
To remediate this vulnerability, upgrade all affected Matrix synapse dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
pip install matrix-synapse>=1.23.1Run the following command in your project directory to verify that all resolved dependencies use the patched release:
pip show matrix-synapseHow to Check if You Are Affected
To determine whether your Python environment is affected by CVE-2020-26257, inspect your installed packages using pip:
pip show matrix-synapseAnalyze the terminal output to locate any version of Matrix synapse in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.23.1), your application is affected.
Note: The pip show matrix-synapse command checks currently installed packages in your active Python environment.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Matrix synapse, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2020-26257 Affected Matrix synapse Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
matrix-synapse
|
PyPI |
< 1.23.1
|
1.23.1
|
References
Frequently Asked Questions
What is CVE-2020-26257?
Which Matrix synapse versions are affected?
What version fixes CVE-2020-26257?
Is matrix-synapse affected?
What is the CVSS score of CVE-2020-26257?
What CWE is associated with CVE-2020-26257?
How can I check PyPI dependencies for CVE-2020-26257?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-hxmp-pqch-c8mm",
"modified" : "2024-09-24T17:44:50Z",
"published" : "2020-12-09T18:21:29Z",
"aliases" : [ "CVE-2020-26257" ],
"summary" : "Denial of service attack via incorrect parameters in Matrix Synapse",
"details" : "### Impact\n\nA malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a `/send_join`, `/send_leave`, `/invite` or `/exchange_third_party_invite` request.\n\nThis can lead to a denial of service in which future events will not be correctly sent to other servers over federation.\n\nThis affects any server which accepts federation requests from untrusted servers.\n\n### Patches\n\nIssue is resolved by https://github.com/matrix-org/synapse/pull/8776.\n\n### Workarounds\n\nHomeserver administrators could limit access to the federation API to trusted servers (for example via `federation_domain_whitelist`).",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
}, {
"type" : "CVSS_V4",
"score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "PyPI",
"name" : "matrix-synapse"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.23.1"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/matrix-org/synapse/security/advisories/GHSA-hxmp-pqch-c8mm"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-26257"
}, {
"type" : "WEB",
"url" : "https://github.com/matrix-org/synapse/pull/8776"
}, {
"type" : "WEB",
"url" : "https://github.com/matrix-org/synapse/commit/3ce2f303f15f6ac3dc352298972dc6e04d9b7a8b"
}, {
"type" : "WEB",
"url" : "https://github.com/matrix-org/synapse/blob/develop/CHANGES.md#synapse-1231-2020-12-09"
}, {
"type" : "WEB",
"url" : "https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2020-236.yaml"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DBTIU3ZNBFWZ56V4X7JIAD33V5H2GOMC"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QR4MMYZKX5N5GYGH4H5LBUUC5TLAFHI7"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-400", "CWE-74", "CWE-79" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2020-12-09T18:21:17Z",
"nvd_published_at" : "2020-12-09T19:15:00Z"
}
}