Exploited Ransomware

CVE-2022-41352

Zimbra (Synacor) Collaboration Suite (ZCS) · Email

Synacor Zimbra Collaboration Suite (ZCS) Arbitrary File Upload Vulnerability

At a glance

Exploited. Added to CISA’s catalog of exploited vulnerabilities on October 20, 2022.

Used in ransomware attacks, according to CISA.

Affected product: Zimbra (Synacor) Collaboration Suite (ZCS) (category Email, indicative classification). Name in CISA’s catalog: Synacor Zimbra Collaboration Suite (ZCS).

What should I do?

Apply the security update from Zimbra (Synacor).

Deadline set by CISA for US federal agencies: 21 days (due November 10, 2022). It only binds those agencies, but it is a useful measure of urgency.

Zimbra (Synacor) security advisories page (general page, not the advisory for this vulnerability)
The vendor’s specific advisory is listed in the NVD references: CVE-2022-41352 on the NVD website.

Original text of the required action (CISA)

Apply updates per vendor instructions.

Timeline

September 26, 2022 Vulnerability published Publication date (NVD)
October 20, 2022 Exploitation confirmed Added to CISA’s KEV catalog
November 10, 2022 CISA deadline Remediation deadline set for US federal agencies

The facts, with their sources

Exploitation confirmed: Yes, on October 20, 2022 Date added to the catalog of exploited vulnerabilities. Exploitation itself may have started earlier. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Ransomware: Known use Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Hunt for compromise: Not requested by CISA Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA required action: Apply the security update from Zimbra (Synacor). Rewritten by this site from CISA’s original text. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA deadline: November 10, 2022, 21 days Set for US federal agencies: a measure of urgency, not an obligation elsewhere. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Vulnerability published: September 26, 2022 Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
Product according to CISA: Synacor Zimbra Collaboration Suite (ZCS) Filed by this site under “Email” (indicative classification). Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Technical detail of the score: attack vector, complexity, impact. Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC

Severity and activity

9.8 / 10 CVSS severity: critical

Score from the NVD. Collected Sep 29, 2026.

— Probability of exploitation in the next 30 days (EPSS)

FIRST’s EPSS model. Since exploitation is already confirmed, this figure is mostly useful to compare activity. Collected Sep 29, 2026.

Description

An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0. An attacker can upload arbitrary files through amavis via a cpio loophole (extraction to /opt/zimbra/jetty/webapps/zimbra/public) that can lead to incorrect access to any other user accounts. Zimbra recommends pax over cpio. Also, pax is in the prerequisites of Zimbra on Ubuntu; however, pax is no longer part of a default Red Hat installation after RHEL 6 (or CentOS 6). Once pax is installed, amavis automatically prefers it over cpio.

Synacor Zimbra Collaboration Suite (ZCS) allows an attacker to upload arbitrary files using cpio package to gain incorrect access to any other user accounts.

Summary from CISA (KEV catalog).

CERT-FR advisories

No advisory among the latest CERT-FR publications this site follows. That does not mean there are none.

Information reused under the Open Licence 2.0 (Etalab); the date of last update is shown for each advisory. This site is neither affiliated with nor endorsed by ANSSI.

Sources for this page

CISA KEV catalog: exploitation, date added, required action, deadline, ransomware.
NVD (NIST): CVSS severity, publication date, description, vendor references.
EPSS (FIRST): probability of exploitation.
CERT-FR: advisories and alerts (in French).
Brand and category: indicative classification by this site (method).