MISP renders the source field of a Galaxy Cluster as a clickable hyperlink whenever the stored value passes PHP's FILTER_VALIDATE_URL validation. Because FILTER_VALIDATE_URL accepts the javascript: URI scheme, a user with galaxy editor privileges on the local instance or on a synced instance could store a javascript: URL as the cluster source.
When another user views the affected Galaxy Cluster and clicks the rendered link, the embedded script executes in the victim's browser context, enabling session hijacking, data exfiltration, or actions performed on behalf of the victim.
Preconditions:
- Attacker must hold galaxy editor privileges (local or via sync).
- Victim must view the affected cluster and click the malicious link.
Impact:
- Stored cross-site scripting (XSS) in the victim's browser.
- Potential session theft, credential harvesting, or unauthorized actions within the MISP application.
Affected: <2.5.48.
"}],"value":"MISP renders the source field of a Galaxy Cluster as a clickable hyperlink whenever the stored value passes PHP's FILTER_VALIDATE_URL validation. Because FILTER_VALIDATE_URL accepts the javascript: URI scheme, a user with galaxy editor privileges on the local instance or on a synced instance could store a javascript: URL as the cluster source.\n\nWhen another user views the affected Galaxy Cluster and clicks the rendered link, the embedded script executes in the victim's browser context, enabling session hijacking, data exfiltration, or actions performed on behalf of the victim.\n\nPreconditions:\n\n- Attacker must hold galaxy editor privileges (local or via sync).\n\n- Victim must view the affected cluster and click the malicious link.\n\nImpact:\n\n- Stored cross-site scripting (XSS) in the victim's browser.\n\n- Potential session theft, credential harvesting, or unauthorized actions within the MISP application.\n\nAffected: <2.5.48."}],"impacts":[{"capecId":"CAPEC-64","descriptions":[{"lang":"en","value":"CAPEC-64 XSS - Persistent"}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":6.2,"baseSeverity":"MEDIUM","privilegesRequired":"LOW","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"HIGH","userInteraction":"ACTIVE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","description":"CWE-79 Improper Neutralization of Input in Web Page ('Cross-site Scripting')","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-09-30T14:22:36.271Z","orgId":"5a6e4751-2f3f-4070-9419-94fb35b644e8","shortName":"CIRCL"},"references":[{"name":"Security patch","tags":["patch"],"url":"https://github.com/MISP/MISP/commit/118528767"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"The fix restricts the rendering of the Galaxy Cluster source field as a hyperlink to only http:// and https:// URLs by adding a regular-expression check (preg_match for ^https?://) in addition to the existing FILTER_VALIDATE_URL validation. This prevents javascript: and other non-HTTP URI schemes from being rendered as clickable links, eliminating the stored XSS vector. The change is applied consistently in both the default theme and the Overmind theme.
"}],"value":"The fix restricts the rendering of the Galaxy Cluster source field as a hyperlink to only http:// and https:// URLs by adding a regular-expression check (preg_match for ^https?://) in addition to the existing FILTER_VALIDATE_URL validation. This prevents javascript: and other non-HTTP URI schemes from being rendered as clickable links, eliminating the stored XSS vector. The change is applied consistently in both the default theme and the Overmind theme."}],"title":"MISP Stored Cross-Site Scripting via JavaScript URL in Galaxy Cluster Source Field","x_gcve":[{"extensions":{"bcp-05-x-01":{"ai_annotations":[{"ai_level":"generated","description":"Draft vulnerability metadata was generated from a git-format patch using an Ollama-hosted language model. Human validation is required before publication.","gna_source":1,"models":[{"gna_source":1,"identifier":"qwen3.8:27b","name":"qwen3.8:27b","source":"ollama"}],"review_status":"full","scope":"record","tags":["ai-computer-assisted:llm-generated","ai-computer-assisted:classification"]}]},"bcp-05-x-02":{"x_patch2vuln":{"assumptions":["The affected version boundary is inferred from the tag_version_boundary metadata (v2.5.48, 26 commits after fix); the exact first affected release is not stated in the patch.","PR:L assumes galaxy editor privileges are a non-admin, role-based permission; the exact privilege model is not detailed in the patch.","UI:A assumes the victim must actively click the rendered link; passive rendering without click does not execute the script.","The CAPEC-64 mapping is the closest available pattern for stored XSS; no CAPEC specifically covers URI-scheme-based stored XSS, so CAPEC-64 is the best fit.","The Co-Authored-By line references an AI assistant; it is credited as a tool rather than a human remediation developer."],"capecRationale":[{"capecId":"CAPEC-64","rationale":"The attack pattern involves storing a malicious payload (a javascript: URL) in a persistent data field (galaxy cluster source) that is later rendered in a web page, executing script in the victim's browser upon interaction. This is a textbook persistent/stored XSS. CAPEC-64 is the closest and most precise match in the CAPEC catalog."}],"commit":"11852876773554d79ff57937a235d18a1e4473dc","confidence":"high","credits":[{"lang":"en","type":"reporter","value":"Jeroen Pinoy"},{"lang":"en","type":"remediation developer","value":"iglocska"},{"lang":"en","type":"remediation developer","value":"Claude Opus 5.5 (1M context)"}],"cvssRationale":"AV:N – MISP is a web application accessed over the network. AC:L – no race conditions or special environment needed; storing a javascript: URL is straightforward. AT:N – no manipulation of the attack target required. PR:L – attacker needs galaxy editor privileges (authenticated, non-admin role). UI:A – victim must click the malicious link for script execution. VC/VI/VA:N – the MISP server itself is not directly compromised; impact is on the victim's browser. SC:H – attacker can read cookies, session tokens, and manipulate the DOM in the victim's session. SI:H – attacker can perform actions on behalf of the victim within MISP. SA:N – no direct compromise of the application's security controls or system integrity.","fixSummary":"The fix restricts the rendering of the Galaxy Cluster source field as a hyperlink to only http:// and https:// URLs by adding a regular-expression check (preg_match for ^https?://) in addition to the existing FILTER_VALIDATE_URL validation. This prevents javascript: and other non-HTTP URI schemes from being rendered as clickable links, eliminating the stored XSS vector. The change is applied consistently in both the default theme and the Overmind theme.","generatedAt":"2026-09-30T14:12:32.112077Z","generator":"patch2vuln.py","model":"qwen3.8:27b","modelComparison":{"rankings":[{"agreementScore":9,"assumptionCount":5,"confidence":"high","model":"qwen3.8:27b","score":6}],"selectedModel":"qwen3.8:27b","selectionMethod":"deterministic-consensus-v1","selectionNotice":"The selected result is closest to model consensus; this heuristic does not establish factual correctness and human review remains required."},"patchSha256":"b68dbd6726929ff1680daeae2a273fc346e7075d7ded36195994315c19ccf278","patchSummary":"Two view templates are modified. In app/View/GalaxyClusters/view.ctp, the source value is extracted into a local variable and the conditional for rendering an anchor tag now requires both FILTER_VALIDATE_URL and a preg_match against /^https?:\\/\\//i. In app/View/Themed/Overmind/Elements/GalaxyClusters/View/galaxy_clusters_general.ctp, the same preg_match guard is added to the existing FILTER_VALIDATE_URL check. Net effect: only http(s) URLs produce a clickable link; all other values (including javascript:) are rendered as plain escaped text.","patchTruncated":false,"patches":[{"commit":"11852876773554d79ff57937a235d18a1e4473dc","patchSha256":"b68dbd6726929ff1680daeae2a273fc346e7075d7ded36195994315c19ccf278","source":"https://github.com/MISP/MISP/commit/118528767.patch","sourceUrl":"https://github.com/MISP/MISP/commit/118528767.patch","subject":"fix: [security] Link a galaxy cluster source only when it is"}],"source":"https://github.com/MISP/MISP/commit/118528767.patch","subject":"fix: [security] Link a galaxy cluster source only when it is","tagVersionBoundary":{"commits_after_fix":26,"repository":"https://github.com/MISP/MISP","tag":"v2.5.48","version":"2.5.48","version_type":"semver"},"weaknessRationale":[{"cweId":"CWE-79","rationale":"The application renders user-controlled data (the galaxy cluster source field) into an HTML anchor tag without restricting the URI scheme to safe values. Although output is HTML-escaped via h(), the href attribute still accepts javascript: URIs, resulting in stored XSS. CWE-79 is the narrowest defensible mapping."}]}}},"recordType":"advisory","vulnId":"GCVE-1-2026-20256"}]}},"cveMetadata":{"assignerOrgId":"5a6e4751-2f3f-4070-9419-94fb35b644e8","assignerShortName":"CIRCL","cveId":"CVE-2026-103388","datePublished":"2026-09-30T14:22:36.271Z","dateReserved":"2026-09-30T14:22:32.098Z","dateUpdated":"2026-09-30T15:28:06.980Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-30 15:22:27","lastModifiedDate":"2026-09-30 16:17:08","problem_types":["CWE-79","CWE-79 CWE-79 Improper Neutralization of Input in Web Page ('Cross-site Scripting')"],"metrics":{"cvssMetricV40":[{"source":"5a6e4751-2f3f-4070-9419-94fb35b644e8","type":"Secondary","cvssData":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/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","baseScore":6.2,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"LOW","userInteraction":"ACTIVE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"HIGH","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"}}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-30T14:58:39.451751Z","id":"CVE-2026-103388","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"103388","Ordinal":"1","Title":"MISP Stored Cross-Site Scripting via JavaScript URL in Galaxy Cl","CVE":"CVE-2026-103388","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"103388","Ordinal":"1","NoteData":"MISP renders the source field of a Galaxy Cluster as a clickable hyperlink whenever the stored value passes PHP's FILTER_VALIDATE_URL validation. Because FILTER_VALIDATE_URL accepts the javascript: URI scheme, a user with galaxy editor privileges on the local instance or on a synced instance could store a javascript: URL as the cluster source.\n\nWhen another user views the affected Galaxy Cluster and clicks the rendered link, the embedded script executes in the victim's browser context, enabling session hijacking, data exfiltration, or actions performed on behalf of the victim.\n\nPreconditions:\n\n- Attacker must hold galaxy editor privileges (local or via sync).\n\n- Victim must view the affected cluster and click the malicious link.\n\nImpact:\n\n- Stored cross-site scripting (XSS) in the victim's browser.\n\n- Potential session theft, credential harvesting, or unauthorized actions within the MISP application.\n\nAffected: <2.5.48.","Type":"Description","Title":"MISP Stored Cross-Site Scripting via JavaScript URL in Galaxy Cl"}]}}}