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2 vulnerabilities found for discourse-activity-pub by discourse
CVE-2026-55103 (GCVE-0-2026-55103)
Vulnerability from nvd – Published: 2026-10-15 17:05 – Updated: 2026-10-15 17:06
VLAI
EPSS
VEX
Title
Discourse ActivityPub: Fix inbound actor validation and apply outbound request SSRF hardening
Summary
Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and owns the referenced federated post. A remote attacker can exploit these missing identity and ownership checks to edit, delete, or reply to federated posts without the required permissions. This vulnerability is fixed with commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5.
Severity
8.6 (High)
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/discourse/discourse-activity-p… | x_refsource_CONFIRM |
| https://github.com/discourse/discourse-activity-p… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| discourse | discourse-activity-pub |
Affected:
< 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5
|
{
"containers": {
"cna": {
"affected": [
{
"product": "discourse-activity-pub",
"vendor": "discourse",
"versions": [
{
"status": "affected",
"version": "\u003c 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and owns the referenced federated post. A remote attacker can exploit these missing identity and ownership checks to edit, delete, or reply to federated posts without the required permissions. This vulnerability is fixed with commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 8.6,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-345",
"description": "CWE-345: Insufficient Verification of Data Authenticity",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-863",
"description": "CWE-863: Incorrect Authorization",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-15T17:06:04.086Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/discourse/discourse-activity-pub/security/advisories/GHSA-jw39-rch6-mhwf",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/discourse/discourse-activity-pub/security/advisories/GHSA-jw39-rch6-mhwf"
},
{
"name": "https://github.com/discourse/discourse-activity-pub/commit/1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/discourse/discourse-activity-pub/commit/1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5"
}
],
"source": {
"advisory": "GHSA-jw39-rch6-mhwf",
"discovery": "UNKNOWN"
},
"title": "Discourse ActivityPub: Fix inbound actor validation and apply outbound request SSRF hardening"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-55103",
"datePublished": "2026-10-15T17:05:41.414Z",
"dateReserved": "2026-06-16T14:41:54.579Z",
"dateUpdated": "2026-10-15T17:06:04.086Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
CVE-2026-55103 (GCVE-0-2026-55103)
Vulnerability from cvelistv5 – Published: 2026-10-15 17:05 – Updated: 2026-10-15 17:06
VLAI
EPSS
VEX
Title
Discourse ActivityPub: Fix inbound actor validation and apply outbound request SSRF hardening
Summary
Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and owns the referenced federated post. A remote attacker can exploit these missing identity and ownership checks to edit, delete, or reply to federated posts without the required permissions. This vulnerability is fixed with commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5.
Severity
8.6 (High)
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/discourse/discourse-activity-p… | x_refsource_CONFIRM |
| https://github.com/discourse/discourse-activity-p… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| discourse | discourse-activity-pub |
Affected:
< 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5
|
{
"containers": {
"cna": {
"affected": [
{
"product": "discourse-activity-pub",
"vendor": "discourse",
"versions": [
{
"status": "affected",
"version": "\u003c 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and owns the referenced federated post. A remote attacker can exploit these missing identity and ownership checks to edit, delete, or reply to federated posts without the required permissions. This vulnerability is fixed with commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 8.6,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-345",
"description": "CWE-345: Insufficient Verification of Data Authenticity",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-863",
"description": "CWE-863: Incorrect Authorization",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-15T17:06:04.086Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/discourse/discourse-activity-pub/security/advisories/GHSA-jw39-rch6-mhwf",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/discourse/discourse-activity-pub/security/advisories/GHSA-jw39-rch6-mhwf"
},
{
"name": "https://github.com/discourse/discourse-activity-pub/commit/1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/discourse/discourse-activity-pub/commit/1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5"
}
],
"source": {
"advisory": "GHSA-jw39-rch6-mhwf",
"discovery": "UNKNOWN"
},
"title": "Discourse ActivityPub: Fix inbound actor validation and apply outbound request SSRF hardening"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-55103",
"datePublished": "2026-10-15T17:05:41.414Z",
"dateReserved": "2026-06-16T14:41:54.579Z",
"dateUpdated": "2026-10-15T17:06:04.086Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}