Medium
Synapse CPU starvation (Denial of Service)
Type: advisorySources: OSV
Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. This vulnerability is fixed in 1.152.1.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-45078
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 21:16 UTC · Revision 1
Source evidence
Synapse CPU starvation (Denial of Service)
core-osv · Original sourcePublished 28 May 2026, 15:52 UTC
Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. This vulnerability is fixed in 1.152.1.
osv:CVE-2026-45078
Complete source record
{
"id": "faf63e6dcd01498d48b9e710473d3147473ffe7428f3135b3872f5904d3a7b60",
"url": "https://osv.dev/vulnerability/CVE-2026-45078",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Synapse CPU starvation (Denial of Service)",
"summary": "Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. This vulnerability is fixed in 1.152.1.",
"evidence": "osv:CVE-2026-45078",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-45078",
"aliases": [
"CVE-2026-45078",
"GHSA-8q93-326v-3m7g",
"PYSEC-2026-191"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/element-hq/synapse",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "d97b5b9e21681792d78c5d58243fc483c664b66e"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "1.152.1"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"cpe": "cpe:2.3:a:element:synapse:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "1.152.1"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
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],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-45078.json"
}
}
],
"modified": "2026-10-28T02:30:39.622266198Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45078.json",
"https://github.com/element-hq/synapse/security/advisories/GHSA-8q93-326v-3m7g",
"https://nvd.nist.gov/vuln/detail/CVE-2026-45078"
],
"provider_metadata": {
"cwe_ids": [
"CWE-770"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45078.json"
}
},
"related_cves": [
{
"value": "CVE-2026-45078",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 507137,
"published_at": "2026-05-28T15:52:04.765+00:00"
}