High
Security advisory
Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2018-10657
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 10:01 UTC · Revision 1
Source evidence
Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.
osv:CVE-2018-10657
Complete source record
{
"id": "6ec46b9e3e7c850a5af2b6c606d80fc716f6a7d40f826e1ae0f991b7c0c921b9",
"url": "https://osv.dev/vulnerability/CVE-2018-10657",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2018-10657",
"summary": "Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.",
"evidence": "osv:CVE-2018-10657",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2018-10657",
"aliases": [
"CVE-2018-10657",
"GHSA-vmcc-4p4x-x7wg",
"PYSEC-2026-846"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/matrix-org/synapse",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "8e6bd0e32456e66ec8df3af62ecacf291cf4632f"
},
{
"fixed": "33f469ba19586bbafa0cf2c7d7c35463bdab87eb"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "0.28.1"
}
],
"source": "CPE_RANGE"
},
{
"range": [
{
"fixed": "33f469ba19586bbafa0cf2c7d7c35463bdab87eb"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"v0.28.0",
"v0.28.0-rc1",
"v0.25.0-rc1",
"v0.23.0-rc2",
"v0.23.0-rc1",
"v0.18.5",
"v0.18.4",
"v0.18.3",
"v0.18.2",
"v0.18.1",
"v0.18.0",
"v0.17.3",
"v0.17.2",
"v0.17.1",
"v0.17.0",
"v0.16.1-r1",
"v0.16.1",
"v0.16.0",
"v0.14.0",
"v0.13.3",
"v0.13.2",
"v0.13.1",
"v0.12.0",
"v0.11.1",
"v0.11.0-r2",
"v0.11.0-r1",
"v0.11.0",
"v0.10.0-r2",
"v0.10.0-r1",
"v0.10.0",
"v0.9.3",
"v0.9.2-r2",
"v0.9.2-r1",
"v0.9.2",
"v0.9.1",
"v0.9.0-r5",
"v0.9.0-r4",
"v0.9.0-r3",
"v0.9.0-r2",
"v0.9.0-r1",
"v0.9.0",
"v0.8.1-r4",
"v0.8.1-r3",
"v0.8.1-r2",
"v0.8.1-r1",
"v0.8.1",
"v0.8.0",
"v0.7.1-r4",
"v0.7.1-r3",
"v0.7.1-r2",
"v0.7.1-r1",
"v0.7.1",
"v0.7.0f",
"v0.7.0e",
"v0.7.0d",
"v0.7.0c",
"v0.7.0b",
"v0.7.0a",
"v0.7.0",
"v0.6.1f",
"v0.6.1e",
"v0.6.1d",
"v0.6.1c",
"v0.6.1b",
"v0.6.1a",
"v0.6.1",
"v0.6.0b",
"v0.6.0a",
"v0.6.0",
"v0.5.4a",
"v0.5.4",
"v0.5.3c",
"v0.5.3b",
"v0.5.3a",
"v0.5.3",
"v0.5.2",
"v0.5.1",
"v0.5.0",
"v0.4.2",
"v0.4.1",
"v0.3.4",
"v0.3.3",
"v0.3.0",
"v0.2.2",
"v0.2.1a",
"v0.2.1",
"v0.2.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-10657.json"
}
}
],
"modified": "2026-10-20T10:49:42.555416133Z",
"provider": "osv",
"references": [
"https://matrix.org/blog/2018/05/01/security-update-synapse-0-28-1/",
"https://github.com/matrix-org/synapse/commit/33f469ba19586bbafa0cf2c7d7c35463bdab87eb"
],
"provider_metadata": {}
},
"related_cves": [
{
"value": "CVE-2018-10657",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 380720,
"published_at": "2018-05-02T16:29:00.233+00:00"
}