CVE-2026-72724 (GCVE-0-2026-72724)
Vulnerability from cvelistv5 – Published: 2026-08-10 15:59 – Updated: 2026-08-11 01:57
VLAI
EPSS
VEX
Title
Discourse: Private Chat Threat Message Disclosure via Chat Onebox Channel/Threat ID Mismatch
Summary
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, plugins/chat/lib/chat/onebox_handler.rb resolves Chat::Thread by route thread_id independently of the route channel_id before checking whether the user can preview the selected chat channel. An authenticated user can pair a public channel ID with a private thread ID in a /onebox.json request and obtain private thread message content. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.
Severity
4.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-11 01:57 UTC
CWE
- CWE-639 - Authorization Bypass Through User-Controlled Key
Assigner
References
9 references
| URL | Tags |
|---|---|
| https://github.com/discourse/discourse/security/a… | x_refsource_CONFIRM |
| https://github.com/discourse/discourse/pull/42091 | x_refsource_MISC |
| https://github.com/discourse/discourse/pull/42092 | x_refsource_MISC |
| https://github.com/discourse/discourse/pull/42093 | x_refsource_MISC |
| https://github.com/discourse/discourse/pull/42094 | x_refsource_MISC |
| https://github.com/discourse/discourse/commit/127… | x_refsource_MISC |
| https://github.com/discourse/discourse/commit/45a… | x_refsource_MISC |
| https://github.com/discourse/discourse/commit/49e… | x_refsource_MISC |
| https://github.com/discourse/discourse/commit/dc5… | x_refsource_MISC |
Impacted products
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"vendor": "discourse",
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"version": "\u003c 2026.1.6"
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"version": "\u003e= 2026.5.0-latest, \u003c 2026.5.2"
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{
"status": "affected",
"version": "\u003e= 2026.6.0-latest, \u003c 2026.6.1"
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"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
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{
"name": "https://github.com/discourse/discourse/security/advisories/GHSA-8g98-fvfc-9w48",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/discourse/discourse/security/advisories/GHSA-8g98-fvfc-9w48"
},
{
"name": "https://github.com/discourse/discourse/pull/42091",
"tags": [
"x_refsource_MISC"
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"url": "https://github.com/discourse/discourse/pull/42091"
},
{
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"x_refsource_MISC"
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},
{
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"tags": [
"x_refsource_MISC"
],
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},
{
"name": "https://github.com/discourse/discourse/pull/42094",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/discourse/discourse/pull/42094"
},
{
"name": "https://github.com/discourse/discourse/commit/1276d7032af8803956c74ae87ccfd976938dcd75",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/discourse/discourse/commit/1276d7032af8803956c74ae87ccfd976938dcd75"
},
{
"name": "https://github.com/discourse/discourse/commit/45ab6d54076de9ca4965888974d4416d5b48e83c",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/discourse/discourse/commit/45ab6d54076de9ca4965888974d4416d5b48e83c"
},
{
"name": "https://github.com/discourse/discourse/commit/49efe1d7f098f2ce7301908815a211cc9248270f",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/discourse/discourse/commit/49efe1d7f098f2ce7301908815a211cc9248270f"
},
{
"name": "https://github.com/discourse/discourse/commit/dc54846f0754799591717b6018343e49524e41ce",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/discourse/discourse/commit/dc54846f0754799591717b6018343e49524e41ce"
}
],
"source": {
"advisory": "GHSA-8g98-fvfc-9w48",
"discovery": "UNKNOWN"
},
"title": "Discourse: Private Chat Threat Message Disclosure via Chat Onebox Channel/Threat ID Mismatch"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-72724",
"datePublished": "2026-08-10T15:59:53.965Z",
"dateReserved": "2026-08-10T13:48:09.545Z",
"dateUpdated": "2026-08-11T01:57:42.639Z",
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"date": "2026-09-17",
"epss": "0.00458",
"percentile": "0.38882"
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"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"product": "discourse",
"vendor": "discourse",
"versions": [
{
"status": "affected",
"version": "\u003c 2026.1.6"
},
{
"status": "affected",
"version": "\u003e= 2026.5.0-latest, \u003c 2026.5.2"
},
{
"status": "affected",
"version": "\u003e= 2026.6.0-latest, \u003c 2026.6.1"
},
{
"status": "affected",
"version": "\u003e= 2026.7.0-latest, \u003c 2026.7.0"
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}
],
"id": "CVE-2026-72724",
"lastModified": "2026-09-08T20:54:37.790",
"metrics": {
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"attackVector": "NETWORK",
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"baseScore": 4.3,
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"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
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},
"published": "2026-08-10T16:19:49.810",
"references": [
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"source": "security-advisories@github.com",
"url": "https://github.com/discourse/discourse/commit/1276d7032af8803956c74ae87ccfd976938dcd75"
},
{
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"url": "https://github.com/discourse/discourse/commit/45ab6d54076de9ca4965888974d4416d5b48e83c"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/discourse/discourse/commit/49efe1d7f098f2ce7301908815a211cc9248270f"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/discourse/discourse/commit/dc54846f0754799591717b6018343e49524e41ce"
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{
"source": "security-advisories@github.com",
"url": "https://github.com/discourse/discourse/pull/42091"
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"vulnrichment": {
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"cna": {
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"vendor": "discourse",
"versions": [
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],
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}
],
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"confidentialityImpact": "LOW",
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],
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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.
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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.
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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.
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