Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders
Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools like Ghostscript for processing. This significantly expands the attack surface in a historically vulnerable area, presenting a risk that far outweighs the benefit, particularly since these formats are rarely used on the open web or within the Matrix ecosystem. Synapse 1.120.1 addresses the issue by restricting thumbnail generation to images in the following widely used formats: PNG, JPEG, GIF, and WebP. This vulnerability is fixed in 1.120.1.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2024-53863
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 20:40 UTC · Revision 1
Source evidence
Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders
core-osv · Original sourcePublished 3 Dec 2024, 16:48 UTC
Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools like Ghostscript for processing. This significantly expands the attack surface in a historically vulnerable area, presenting a risk that far outweighs the benefit, particularly since these formats are rarely used on the open web or within the Matrix ecosystem. Synapse 1.120.1 addresses the issue by restricting thumbnail generation to images in the following widely used formats: PNG, JPEG, GIF, and WebP. This vulnerability is fixed in 1.120.1.
osv:CVE-2024-53863
Complete source record
{
"id": "c362c3fa465ea27ebababc92773e2bb7db9899fbf7e77cfbb148ea913aaf863e",
"url": "https://osv.dev/vulnerability/CVE-2024-53863",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders",
"summary": "Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools like Ghostscript for processing. This significantly expands the attack surface in a historically vulnerable area, presenting a risk that far outweighs the benefit, particularly since these formats are rarely used on the open web or within the Matrix ecosystem. Synapse 1.120.1 addresses the issue by restricting thumbnail generation to images in the following widely used formats: PNG, JPEG, GIF, and WebP. This vulnerability is fixed in 1.120.1.",
"evidence": "osv:CVE-2024-53863",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2024-53863",
"aliases": [
"CVE-2024-53863",
"GHSA-vp6v-whfm-rv3g",
"PYSEC-2026-1615"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/element-hq/synapse",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "fe3d88b833f76742874642c119b14b788341c905"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "1.120.1"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
}
]
}
}
],
"versions": [
"v1.120.0",
"v1.120.0rc1",
"v1.116.0rc1",
"v1.115.0rc1",
"v1.114.0rc1",
"v1.112.0rc1",
"v1.111.0rc1",
"v1.106.0rc1",
"v1.105.0rc1",
"v1.104.0rc1",
"v1.103.0rc1",
"v1.101.0rc1",
"v1.100.0rc3",
"v1.100.0rc2",
"v1.100.0rc1",
"v1.99.0rc1",
"v1.98.0rc1",
"v1.95.0rc1",
"v1.94.0rc1",
"v1.90.0rc1",
"v1.88.0rc1",
"v1.87.0rc1",
"v1.84.0rc1",
"v1.81.0rc1",
"v1.79.0rc1",
"v1.78.0rc1",
"v1.76.0rc1",
"v1.75.0rc1",
"v1.63.0rc1",
"v1.62.0rc1",
"v1.52.0rc1",
"v1.49.0rc1",
"v1.40.0rc1",
"v1.36.0rc1",
"v1.35.0rc1",
"v1.34.0rc1",
"v1.32.0rc1",
"v1.31.0rc1",
"v1.30.0rc1",
"v1.29.0rc1",
"v1.27.0rc1",
"v1.24.0rc1",
"v1.23.0rc1",
"v1.17.0rc1",
"v1.18.0rc1",
"v1.16.0rc1",
"v1.15.0rc1",
"v1.14.0rc1",
"v1.12.0rc1",
"v1.6.0rc1",
"v1.11.0rc1",
"v1.3.0rc1",
"v1.1.0rc2",
"v1.1.0rc1",
"v1.10.0rc1",
"v1.9.0rc1",
"v1.9.0.dev2",
"v1.9.0.dev1",
"v1.8.0rc1",
"v1.5.0rc1",
"v1.4.0rc1",
"v0.99.5.1.dev0",
"v0.99.4rc1",
"v0.99.2rc1",
"v0.99.1rc1",
"hhs-8",
"hhs-7",
"hhs-6",
"hhs-5",
"hhs-3",
"hhs-2",
"hhs-1",
"v0.32.2",
"v0.32.0",
"v0.32.0rc1",
"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-2024-53863.json"
}
}
],
"modified": "2026-10-28T02:30:39.157258761Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/53xxx/CVE-2024-53863.json",
"https://github.com/element-hq/synapse/security/advisories/GHSA-vp6v-whfm-rv3g",
"https://nvd.nist.gov/vuln/detail/CVE-2024-53863"
],
"provider_metadata": {
"cwe_ids": [
"CWE-434"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/53xxx/CVE-2024-53863.json"
}
},
"related_cves": [
{
"value": "CVE-2024-53863",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 506784,
"published_at": "2024-12-03T16:48:29.722+00:00"
}