CVE-2026-31809

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{"affected": [{"affectedData": [{"product": "siyuan", "vendor": "siyuan-note", "versions": [{"status": "affected", "version": "< 3.5.10"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*", "matchCriteriaId": "0E7B145F-4786-4534-B4D6-A947F4CD06FE", "versionEndExcluding": "3.5.10", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) checks href attributes for the javascript: prefix using strings.HasPrefix(). However, inserting ASCII tab (&#9;), newline (&#10;), or carriage return (&#13;) characters inside the javascript: string bypasses this prefix check. Browsers strip these characters per the WHATWG URL specification before parsing the URL scheme, so the JavaScript still executes. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint, creating a reflected XSS. This is a second bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in 3.5.10."}, {"lang": "es", "value": "SiYuan es un sistema de gesti\u00f3n de conocimiento personal. Antes de la versi\u00f3n 3.5.10, el saneador de SVG de SiYuan (SanitizeSVG) verifica los atributos href en busca del prefijo javascript: utilizando strings.HasPrefix(). Sin embargo, la inserci\u00f3n de caracteres de tabulaci\u00f3n ASCII (\t), nueva l\u00ednea (\n) o retorno de carro (\r) dentro de la cadena javascript: elude esta verificaci\u00f3n de prefijo. Los navegadores eliminan estos caracteres seg\u00fan la especificaci\u00f3n de URL de WHATWG antes de analizar el esquema de URL, por lo que el JavaScript a\u00fan se ejecuta. Esto permite a un atacante inyectar JavaScript ejecutable en el endpoint no autenticado /API/icon/getDynamicIcon, creando un XSS reflejado. Este es un segundo bypass de la correcci\u00f3n para CVE-2026-29183 (corregido en la v3.5.9). Esta vulnerabilidad se corrige en la versi\u00f3n 3.5.10."}], "id": "CVE-2026-31809", "lastModified": "2026-06-17T10:34:30.170", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.1, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 2.7, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.4, "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": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/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": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-31809", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-03-11T15:23:59.939812Z", "version": "2.0.3"}}]}, "published": "2026-03-10T21:16:50.337", "references": [{"source": "security-advisories@github.com", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-pmc9-f5qr-2pcr"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,3.5.10)"}}], "enrichment": {"confidence": 84.0, "confidence_source": "matching", "scores": [{"score": 84.0, "source": "matching"}]}, "original": {"product": "siyuan", "source": "cna", "vendor": "siyuan-note"}, "product": "siyuan", "vendor": "siyuan"}], "analysis": {"en": {"generated_at": "2026-04-17T11:36:13.788486+00:00", "value": {"mitigation_remediation": ["Upgrade SiYuan Note to version 3.5.10 or later, where the SVG sanitizer has been corrected.", "Limit or block access to the /api/icon/getDynamicIcon endpoint so that only authenticated clients can request icons.", "Deploy a web application firewall or reverse proxy rule that rejects or normalizes javascript: URIs with embedded whitespace in SVG files to prevent the sanitization bypass."], "summary": {"action": "Patch Now", "impact": "Reflected XSS via an unauthenticated SVG endpoint"}, "threat_synthesis": {"affected_systems": "All releases of SiYuan Note before version 3.5.10 are vulnerable. The affected component is the backend SVG sanitization logic that examines href attributes. Any deployment that exposes the unauthenticated /api/icon/getDynamicIcon endpoint is at risk, regardless of whether the server is internally or externally reachable.", "description_and_impact": "SiYuan\u2019s SVG sanitizer validates href attributes by checking if they start with the string \"javascript:\". In versions prior to 3.5.10, inserting characters such as ASCII tab, newline, or carriage return within the prefix bypasses this check. Browsers strip those whitespace characters before parsing the URL scheme, so the embedded JavaScript is treated as a valid javascript: URI and executed in the victim\u2019s browser when the SVG is rendered. The flaw therefore allows an attacker to inject and execute arbitrary script code through the public /api/icon/getDynamicIcon endpoint.", "risk_and_exploitability": "The CVSS score of 6.4 indicates moderate severity. The EPSS score of less than 1\u202f% suggests a low probability of exploitation at the time of analysis, and the vulnerability is not listed in CISA\u2019s KEV catalog. The likely attack vector is an unauthenticated request to the /api/icon/getDynamicIcon endpoint, where a crafted SVG containing a javascript: URI with embedded whitespace is fetched and rendered in a browser that visits the URL. The vulnerability\u2019s impact is the execution of arbitrary JavaScript in the victim\u2019s browser context."}}}}, "created": "2026-03-11T11:42:07.168958+00:00", "updated": "2026-04-17T11:45:06.228167+00:00", "vendors": ["siyuan", "siyuan$PRODUCT$siyuan"]}