{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-66912", "assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6", "state": "PUBLISHED", "assignerShortName": "CERT-PL", "dateReserved": "2026-07-28T12:14:18.398Z", "datePublished": "2026-10-29T15:22:22.773Z", "dateUpdated": "2026-10-29T15:22:22.773Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6", "shortName": "CERT-PL", "dateUpdated": "2026-10-29T15:22:22.773Z"}, "title": "Stored Cross-Site Scripting in Zimbra", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-79", "description": "CWE-79 Improper neutralization of input during web page generation ('cross-site scripting')", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-592", "descriptions": [{"lang": "en", "value": "CAPEC-592 Stored XSS"}]}], "affected": [{"vendor": "Synacor", "product": "Zimbra Collaboration", "versions": [{"status": "affected", "version": "0", "lessThan": "10.1.21", "versionType": "semver"}], "defaultStatus": "unaffected"}], "cpeApplicability": [{"operator": "OR", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:synacor:zimbra_collaboration:*:*:*:*:*:*:*:*", "versionStartIncluding": "0", "versionEndExcluding": "10.1.21"}]}]}], "descriptions": [{"lang": "en", "value": "Zimbra is vulnerable to Stored Cross-Site Scripting (XSS) via the From email header during HTML reply composition in Classic UI. Due to insufficient sanitization of the From header value, a remote attacker can send a crafted email containing a malicious From header with an embedded JavaScript payload. When the victim opens the message in Classic UI and clicks Reply while composing in HTML mode with reply headers disabled, the unsanitized From header content is rendered as HTML and the JavaScript payload executes in the victim's browser, potentially allowing the attacker to steal session information or perform actions on behalf of the victim.\u00a0This issue was fixed in version\u00a010.1.21", "supportingMedia": [{"type": "text/html", "base64": false, "value": "Zimbra is vulnerable to Stored Cross-Site Scripting (XSS) via the From email header during HTML reply composition in Classic UI. Due to insufficient sanitization of the From header value, a remote attacker can send a crafted email containing a malicious From header with an embedded JavaScript payload. When the victim opens the message in Classic UI and clicks Reply while composing in HTML mode with reply headers disabled, the unsanitized From header content is rendered as HTML and the JavaScript payload executes in the victim's browser, potentially allowing the attacker to steal session information or perform actions on behalf of the victim.&nbsp;<div>This issue was fixed in version&nbsp;10.1.21</div>"}]}], "references": [{"url": "https://cert.pl/en/posts/2026/10/CVE-2026-66911", "tags": ["third-party-advisory"]}, {"url": "https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories", "tags": ["release-notes"]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "MEDIUM", "baseScore": 5.3, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"}}], "credits": [{"lang": "en", "value": "Mateusz Borkowski (CERT.PL)", "type": "finder"}], "source": {"discovery": "INTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.3"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Zimbra Collaboration", "vendor": "Synacor", "versions": [{"lessThan": "10.1.21", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "cvd@cert.pl"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Zimbra is vulnerable to Stored Cross-Site Scripting (XSS) via the From email header during HTML reply composition in Classic UI. Due to insufficient sanitization of the From header value, a remote attacker can send a crafted email containing a malicious From header with an embedded JavaScript payload. When the victim opens the message in Classic UI and clicks Reply while composing in HTML mode with reply headers disabled, the unsanitized From header content is rendered as HTML and the JavaScript payload executes in the victim's browser, potentially allowing the attacker to steal session information or perform actions on behalf of the victim.\u00a0This issue was fixed in version\u00a010.1.21"}], "id": "CVE-2026-66912", "lastModified": "2026-10-29T16:29:56.553", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 5.3, "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": "LOW", "subIntegrityImpact": "LOW", "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:L/SI:L/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": "cvd@cert.pl", "type": "Secondary"}]}, "published": "2026-10-29T16:18:15.530", "references": [{"source": "cvd@cert.pl", "url": "https://cert.pl/en/posts/2026/10/CVE-2026-66911"}, {"source": "cvd@cert.pl", "url": "https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories"}], "sourceIdentifier": "cvd@cert.pl", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "cvd@cert.pl", "type": "Primary"}]}

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{}