CVE-2026-73313 (GCVE-0-2026-73313)
Vulnerability from cvelistv5 – Published: 2026-09-08 13:17 – Updated: 2026-09-09 01:08
VLAI
EPSS
VEX
Title
XenForo < 2.3.13 MFA Bypass via Passkey TFA Provider
Summary
XenForo before 2.3.13 contains a multi-factor authentication bypass vulnerability in the passkey TFA provider that allows an authenticated attacker to complete login as another user by submitting their own registered passkey credential during the WebAuthn assertion step. The passkey verification path performs a global credential lookup without validating that the matched credential belongs to the user whose login is pending, enabling an attacker who knows a target account's password to sign the challenge with their own passkey and bypass multi-factor authentication on both public forum and ACP login paths.
Severity
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
5 references
| URL | Tags |
|---|---|
| https://xenforo.com/community/threads/security-fi… | vendor-advisorypatch |
| https://xenforo.com/community/threads/xenforo-2-3… | release-notes |
| https://bombobombone.github.io/posts/cve-2026-73313/ | technical-description |
| https://github.com/BomboBombone/CVE-2026-73313 | exploit |
| https://www.vulncheck.com/advisories/xenforo-mfa-… | third-party-advisory |
Impacted products
Date Public
2026-09-07 00:00
{
"containers": {
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"affected": [
{
"defaultStatus": "unaffected",
"product": "XenForo",
"vendor": "XenForo",
"versions": [
{
"lessThan": "2.3.13",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Marco Paciaroni (BomboBombone)"
},
{
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"type": "coordinator",
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}
],
"datePublic": "2026-09-07T00:00:00.000Z",
"descriptions": [
{
"lang": "en",
"value": "XenForo before 2.3.13 contains a multi-factor authentication bypass vulnerability in the passkey TFA provider that allows an authenticated attacker to complete login as another user by submitting their own registered passkey credential during the WebAuthn assertion step. The passkey verification path performs a global credential lookup without validating that the matched credential belongs to the user whose login is pending, enabling an attacker who knows a target account\u0027s password to sign the challenge with their own passkey and bypass multi-factor authentication on both public forum and ACP login paths."
}
],
"metrics": [
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"cvssV4_0": {
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"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "HIGH",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 7.6,
"baseSeverity": "HIGH",
"exploitMaturity": "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:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "HIGH",
"vulnIntegrityImpact": "HIGH",
"vulnerabilityResponseEffort": "NOT_DEFINED"
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"scenarios": [
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"confidentialityImpact": "HIGH",
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"scope": "UNCHANGED",
"userInteraction": "NONE",
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"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-863",
"description": "Incorrect Authorization",
"lang": "en",
"type": "CWE"
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],
"providerMetadata": {
"dateUpdated": "2026-09-09T01:08:06.154Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
},
"references": [
{
"name": "Vendor Advisory",
"tags": [
"vendor-advisory",
"patch"
],
"url": "https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/"
},
{
"name": "Release Notes",
"tags": [
"release-notes"
],
"url": "https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/"
},
{
"name": "Researcher Advisory",
"tags": [
"technical-description"
],
"url": "https://bombobombone.github.io/posts/cve-2026-73313/"
},
{
"name": "Researcher PoC",
"tags": [
"exploit"
],
"url": "https://github.com/BomboBombone/CVE-2026-73313"
},
{
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/xenforo-mfa-bypass-via-passkey-tfa-provider"
}
],
"source": {
"discovery": "UNKNOWN"
},
"title": "XenForo \u003c 2.3.13 MFA Bypass via Passkey TFA Provider",
"x_generator": {
"engine": "vulncheck"
}
}
},
"cveMetadata": {
"assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-73313",
"datePublished": "2026-09-08T13:17:30.351Z",
"dateReserved": "2026-08-11T19:56:20.007Z",
"dateUpdated": "2026-09-09T01:08:06.154Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-73313",
"date": "2026-09-10",
"epss": "0.00385",
"percentile": "0.31837"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-73313\",\"sourceIdentifier\":\"disclosure@vulncheck.com\",\"published\":\"2026-09-08T14:17:25.500\",\"lastModified\":\"2026-09-09T01:16:57.813\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"XenForo before 2.3.13 contains a multi-factor authentication bypass vulnerability in the passkey TFA provider that allows an authenticated attacker to complete login as another user by submitting their own registered passkey credential during the WebAuthn assertion step. The passkey verification path performs a global credential lookup without validating that the matched credential belongs to the user whose login is pending, enabling an attacker who knows a target account\u0027s password to sign the challenge with their own passkey and bypass multi-factor authentication on both public forum and ACP login paths.\"}],\"affected\":[{\"source\":\"disclosure@vulncheck.com\",\"affectedData\":[{\"vendor\":\"XenForo\",\"product\":\"XenForo\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"2.3.13\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/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\",\"baseScore\":7.6,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"cvssMetricV31\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N\",\"baseScore\":6.8,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":1.6,\"impactScore\":5.2}]},\"weaknesses\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-863\"}]}],\"references\":[{\"url\":\"https://bombobombone.github.io/posts/cve-2026-73313/\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/BomboBombone/CVE-2026-73313\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://www.vulncheck.com/advisories/xenforo-mfa-bypass-via-passkey-tfa-provider\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/\",\"source\":\"disclosure@vulncheck.com\"}]}}"
}
}
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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.
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.
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