VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 19 April 2022Ransomware use: known
Synacor Zimbra Collaboration Suite (ZCS)

CVE-2018-6882: Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 19 Apr 2022, 1,484 days after the CVE record was published.

How likely is exploitation in the next 30 days?
29.8%

EPSS score, percentile 98.2 of all scored records

How severe?
6.1 Medium

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 10 May 2022. Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Not stated. The CVE record gives vendor and product as “n/a” and the version as “unspecified”.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: 10 May 2022.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

Affected products and versions

The CVE record does not name affected products or versions: vendor and product are “n/a” and the version is “unspecified”.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that might allow remote attackers to inject arbitrary web script or HTML.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2018-6882 to its Known Exploited Vulnerabilities (KEV) catalog on 19 Apr 2022.
  • CISA marks it as known to be used in ransomware campaigns.
  • The due date CISA sets for the required action is 10 May 2022.
  • The CVE record was published on 27 Mar 2018, 1,484 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 6.1 (Medium), taken from CISA's enrichment of the record.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 29.8% (percentile 98.2), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Cross-site scripting (XSS) vulnerability in the ZmMailMsgView.getAttachmentLinkHtml function in Zimbra Collaboration Suite (ZCS) before 8.7 Patch 1 and 8.8.x before 8.8.7 might allow remote attackers to inject arbitrary web script or HTML via a Content-Location header in an email attachment.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
27 Mar 2018CVE record published
19 Apr 2022Added to CISA KEV
10 May 2022CISA due date for the required action
1 Oct 2026CVE record last updated

References

More exploited Synacor vulnerabilities

  • CVE-2026-73570: Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability (added 21 Aug 2026)
  • CVE-2025-48700: Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability (added 20 Apr 2026)
  • CVE-2025-66376: Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability (added 18 Mar 2026)
  • CVE-2020-7796: Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery Vulnerability (added 17 Feb 2026)
  • CVE-2025-68645: Synacor Zimbra Collaboration Suite (ZCS) PHP Remote File Inclusion Vulnerability (added 22 Jan 2026)
  • CVE-2025-27915: Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability (added 7 Oct 2025)