Evidence dossier

CVE-2025-27915

CVE-2025-27915

57.7–72.7Priority evidence range

As known Jul 19, 2026, 5:00 AM UTCgen-56ccdaf9

Normalized restatement

An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a <details> tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.

State: PUBLISHED
Published: Mar 12, 2025
Updated: Feb 26, 2026
Evidence coverage: 85%

CISA KEVCatalog member

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

FIRST EPSS4.34%

2026-07-18 · v2026.06.15 · percentile 90.1%

Source stateNo scored conflict

Distinct CVSS assessments remain side by side; none are averaged.

Source comparison

Who said what

CISA-ADPindependent enrichment

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CISA ADP Vulnrichment

Jul 19, 2026Original evidence ↗

mitreoriginal assertion

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An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a <details> tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.

Jul 19, 2026Original evidence ↗

CISA KEVoriginal assertion

observed_exploitation

Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability

Jul 19, 2026Original evidence ↗

FIRST EPSSoriginal assertion

model_probability

Probability 0.043440000000; percentile 0.901320000000

Jul 19, 2026Original evidence ↗

Applicability

Cited product scope

Trace impact →

n/an/a

[{"status": "affected", "version": "n/a"}]unknown

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*; start including 10.0.0; end excluding 10.0.13supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*; start including 10.1.0; end excluding 10.1.5supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:-:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p1:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p10:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p11:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p12:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p13:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p14:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p15:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p16:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p17:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p18:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p19:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p2:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p20:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p21:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p22:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p23:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p24:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p24.1:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p25:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p26:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p27:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p28:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p29:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p3:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p30:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p31:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p32:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p33:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p34:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p35:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p36:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p37:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p38:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p39:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p4:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p40:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p41:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p42:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p43:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p5:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p6:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p7:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p8:*:*:*:*:*:*supported

Unknown vendorUnknown product

cpe:2.3:a:synacor:zimbra_collaboration_suite:9.0.0:p9:*:*:*:*:*:*supported

Assessments

CVSS by origin

5.4

134c704f-9b21-4f2e-91b3-4a467353bcc0CVSS 3.1 · role SecondaryCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

5.4

CISA-ADPCVSS 3.1 · role unknownCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Limitations and unknowns

KEV membership is authoritative for the catalog, not proof of exposure in any environment.
EPSS is a dated model probability and not an individual-environment prediction.
Affected or fixed status applies only to the exact cited product and version scope; unresolved scope remains unknown.
NVD-carried upstream facts remain derivative and are not independent corroboration.
Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
Factor D is unknown in Public Core because no accepted canonical mapping-obligation ledger is present.
Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.