CVE-2025-61672 (GCVE-0-2025-61672)
Vulnerability from cvelistv5 – Published: 2025-10-08 14:55 – Updated: 2025-10-15 16:11
VLAI
EPSS
VEX
Title
Synapse: Invalid device keys degrade federation functionality
Summary
Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-10-15 16:10 UTC
CWE
- CWE-1287 - Improper Validation of Specified Type of Input
Assigner
References
6 references
| URL | Tags |
|---|---|
| https://github.com/element-hq/synapse/security/ad… | x_refsource_CONFIRM |
| https://github.com/element-hq/synapse/pull/17097 | x_refsource_MISC |
| https://github.com/element-hq/synapse/commit/26aa… | x_refsource_MISC |
| https://github.com/element-hq/synapse/commit/7069… | x_refsource_MISC |
| https://github.com/element-hq/synapse/releases/ta… | x_refsource_MISC |
| https://github.com/element-hq/synapse/releases/ta… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| element-hq | synapse |
Affected:
< 1.138.3
Affected: = 1.139.0 |
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2025-61672",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2025-10-15T16:10:58.297046Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2025-10-15T16:11:07.284Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "synapse",
"vendor": "element-hq",
"versions": [
{
"status": "affected",
"version": "\u003c 1.138.3"
},
{
"status": "affected",
"version": "= 1.139.0"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"privilegesRequired": "LOW",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-1287",
"description": "CWE-1287: Improper Validation of Specified Type of Input",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2025-10-08T14:55:06.378Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr"
},
{
"name": "https://github.com/element-hq/synapse/pull/17097",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/pull/17097"
},
{
"name": "https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1"
},
{
"name": "https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740"
},
{
"name": "https://github.com/element-hq/synapse/releases/tag/v1.138.3",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/releases/tag/v1.138.3"
},
{
"name": "https://github.com/element-hq/synapse/releases/tag/v1.139.1",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/releases/tag/v1.139.1"
}
],
"source": {
"advisory": "GHSA-fh66-fcv5-jjfr",
"discovery": "UNKNOWN"
},
"title": "Synapse: Invalid device keys degrade federation functionality"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2025-61672",
"datePublished": "2025-10-08T14:55:06.378Z",
"dateReserved": "2025-09-29T20:25:16.180Z",
"dateUpdated": "2025-10-15T16:11:07.284Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2025-61672",
"date": "2026-10-09",
"epss": "0.00466",
"percentile": "0.38363"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"product": "synapse",
"vendor": "element-hq",
"versions": [
{
"status": "affected",
"version": "\u003c 1.138.3"
},
{
"status": "affected",
"version": "= 1.139.0"
}
]
}
],
"source": "security-advisories@github.com"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2."
},
{
"lang": "es",
"value": "Synapse es una implementaci\u00f3n de homeserver de Matrix de c\u00f3digo abierto. La falta de validaci\u00f3n para las claves de dispositivo en Synapse anterior a 1.138.3 y en Synapse 1.139.0 permite a un atacante registrado en el homeserver v\u00edctima degradar la funcionalidad de federaci\u00f3n, rompiendo impredeciblemente la federaci\u00f3n saliente a otros homeservers. El problema est\u00e1 parcheado en Synapse 1.138.3, 1.138.4, 1.139.1 y 1.139.2. Tenga en cuenta que aunque 1.138.3 y 1.139.1 solucionan la vulnerabilidad, introdujeron inadvertidamente una regresi\u00f3n no relacionada. Por esta raz\u00f3n, los mantenedores de Synapse recomiendan omitir estas versiones y actualizar directamente a 1.138.4 y 1.139.2."
}
],
"id": "CVE-2025-61672",
"lastModified": "2026-10-08T13:10:00.200",
"metrics": {
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"privilegesRequired": "LOW",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "security-advisories@github.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2025-61672",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2025-10-15T16:10:58.297046Z",
"version": "2.0.3"
}
}
]
},
"published": "2025-10-08T15:16:25.110",
"references": [
{
"source": "security-advisories@github.com",
"url": "https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/element-hq/synapse/pull/17097"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/element-hq/synapse/releases/tag/v1.138.3"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/element-hq/synapse/releases/tag/v1.139.1"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr"
}
],
"sourceIdentifier": "security-advisories@github.com",
"vulnStatus": "Deferred",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-1287"
}
],
"source": "security-advisories@github.com",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"current_release_date": "2026-06-27T13:40:47+00:00",
"cve": "CVE-2025-61672",
"id": "CVE-2025-61672",
"initial_release_date": "2025-10-08T14:55:06.378000+00:00",
"product_status:known_not_affected": "1",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "matrix-synapse: Synapse: Lack of device key validation leads to federation degradation",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-61672.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2025-10-08T23:22:24Z",
"cve": "CVE-2025-61672",
"id": "CVE-2025-61672",
"initial_release_date": "2025-10-07T23:25:27Z",
"product_status:recommended": "1",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2025-61672",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-61672.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2025-61672",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2025-10-15T16:10:58.297046Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2025-10-08T15:20:42.340Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "synapse",
"vendor": "element-hq",
"versions": [
{
"status": "affected",
"version": "\u003c 1.138.3"
},
{
"status": "affected",
"version": "= 1.139.0"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"privilegesRequired": "LOW",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-1287",
"description": "CWE-1287: Improper Validation of Specified Type of Input",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2025-10-08T14:55:06.378Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr"
},
{
"name": "https://github.com/element-hq/synapse/pull/17097",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/pull/17097"
},
{
"name": "https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1"
},
{
"name": "https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740"
},
{
"name": "https://github.com/element-hq/synapse/releases/tag/v1.138.3",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/releases/tag/v1.138.3"
},
{
"name": "https://github.com/element-hq/synapse/releases/tag/v1.139.1",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/element-hq/synapse/releases/tag/v1.139.1"
}
],
"source": {
"advisory": "GHSA-fh66-fcv5-jjfr",
"discovery": "UNKNOWN"
},
"title": "Synapse: Invalid device keys degrade federation functionality"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2025-61672",
"datePublished": "2025-10-08T14:55:06.378Z",
"dateReserved": "2025-09-29T20:25:16.180Z",
"dateUpdated": "2025-10-15T16:11:07.284Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…