CASCACascade Atlas

Evidence dossier

CVE-2024-27443

CVE-2024-27443

64.1–79.1Priority 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. A Cross-Site Scripting (XSS) vulnerability exists in the CalendarInvite feature of the Zimbra webmail classic user interface, because of improper input validation in the handling of the calendar header. An attacker can exploit this via an email message containing a crafted calendar header with an embedded XSS payload. When a victim views this message in the Zimbra webmail classic interface, the payload is executed in the context of the victim's session, potentially leading to execution of arbitrary JavaScript code.

State
PUBLISHED
Published
Aug 12, 2024
Updated
Oct 21, 2025
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 EPSS19.54%

2026-07-18 · v2026.06.15 · percentile 97.1%

Source stateNo scored conflict

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

Source comparison

Who said what

CISA-ADPindependent enrichment
container

CISA ADP Vulnrichment

mitreoriginal assertion
container

An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0. A Cross-Site Scripting (XSS) vulnerability exists in the CalendarInvite feature of the Zimbra webmail classic user interface, because of improper input validation in the handling of the calendar header. An attacker can exploit this via an email message containing a crafted calendar header with an embedded XSS payload. When a victim views this message in the Zimbra webmail classic interface, the payload is executed in the context of the victim's session, potentially leading to execution of arbitrary JavaScript code.

CISA KEVoriginal assertion
observed_exploitation

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

FIRST EPSSoriginal assertion
model_probability

Probability 0.195430000000; percentile 0.970760000000

Applicability

Cited product scope

Trace impact →
n/an/a
[{"status": "affected", "version": "n/a"}]unknown
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:*:*:*:*:*:*:*:*; start including 10.0.0; end excluding 10.0.7supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:-:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p0:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p1:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p10:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p11:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p12:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p13:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p14:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p15:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p16:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p19:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p2:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p20:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p21:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p23:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p24:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p24.1:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p25:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p26:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p27:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p3:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p30:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p31:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p32:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p33:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p34:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p35:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p36:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p37:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p38:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p4:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p5:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p6:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p7:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p7.1:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p8:*:*:*:*:*:*supported
Unknown vendorUnknown product
cpe:2.3:a:zimbra:collaboration:9.0.0:p9:*:*:*:*:*:*supported

Assessments

CVSS by origin

6.1
nvd@nist.govCVSS 3.1 · role PrimaryCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1
134c704f-9b21-4f2e-91b3-4a467353bcc0CVSS 3.1 · role SecondaryCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1
CISA-ADPCVSS 3.1 · role unknownCVSS:3.1/AV:N/AC:L/PR:N/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.