Threats / Synacor / CVE-2018-6882
CVE-2018-6882
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Synacor Zimbra Collaboration Suite (ZCS) vulnerability
Synacor Zimbra Collaboration Suite contains a cross-site scripting vulnerability allowing remote attackers to inject arbitrary web script or HTML.
Verdict
Today item, not a backlog item.
A reflected or stored XSS flaw in ZCS enables attackers to execute malicious scripts in user browsers, potentially compromising session tokens, credentials, or enabling further attacks. Active exploitation and ransomware campaigns have been documented.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-04-19), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.23717 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Synacor, Zimbra Collaboration Suite (ZCS). Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-79 Cross-site Scripting (XSS) — weakness family: Web / client.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious URL or email containing JavaScript payload targeting a ZCS user.
Business
User credentials, session data, or sensitive collaboration content becomes accessible to the attacker.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I inject persistent XSS into shared documents or messages within the collaboration platform.
Business
Malware or ransomware is distributed across the organization through trusted internal communications.
3
Lateral reach — past segmentation narrative 3
Attacker
I use the XSS to redirect users to credential harvesting pages or trigger drive-by downloads.
Business
Widespread credential compromise and system infection enable lateral movement and data exfiltration.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05