CriticalCVE-2022-41352

    Synacor Zimbra Collaboration Suite (ZCS) Arbitrary File Upload Vulnerability (CVE-2022-41352)

    Published Last modified In CISA KEV since Sources: SingCERT, CVE.org

    What is affected, what to do

    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.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Zimbra Collaboration eq 9.0.0..9.0.0
    • Zimbra Collaboration eq 8.8.15..8.8.15

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: SingCERT, CVE.org

    95.5 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.87

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    255.25 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: ANSSI / CERT-FR, CSA/SingCERT How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    95.5 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    99.87
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is network-reachable without authentication or user interaction. Simply receiving a crafted email is enough to drop a webshell into the publicly served webroot, which gives the attacker access to every mailbox on the server. CISA flags known ransomware use, and exploitation likelihood sits among the very highest of any CVE. Self-hosted Zimbra at public-sector bodies, municipalities, education, and mid-market firms is the typical target. Treat every internet-facing instance on a RHEL/CentOS derivative without pax as critical, patch immediately, and assume it may already be compromised until a webroot hunt proves otherwise.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Establish exposure and platform: Inventory every ZCS 8.8.15 and 9.0 instance and check the underlying OS. Highest risk is RHEL/CentOS 7+ and derivatives such as Rocky and Alma, where pax is not installed by default and amavis falls back to cpio. Check with rpm -q pax or dpkg -l pax.
      • Apply the vendor patch: A patch is available from the vendor — look up the version in the Zimbra security advisory for CVE-2022-41352. Roll it out to all MTA and mailbox nodes.
      • Apply the workaround if you cannot patch immediately: Install pax (dnf install pax or yum install pax; on Ubuntu apt install pax), then restart Zimbra (su - zimbra -c "zmcontrol restart"). From then on, amavis prefers pax over cpio automatically.
      • Hunt for compromise before you clean up: Inspect /opt/zimbra/jetty/webapps/zimbra/public/ and its subdirectories for unknown .jsp files (find /opt/zimbra/jetty/webapps/zimbra/public -name "*.jsp" -newer /opt/zimbra/.install_history). Diff against a clean reference install and preserve evidence (disk image, hashes, timestamps).
      • If you find a webshell: Isolate the host or move it to a quarantine VLAN. Then rotate all mailbox passwords, the zimbra LDAP credentials (zmlocalconfig -s ldap_root_password zimbra_ldap_password), admin accounts, and API/SMTP secrets. Invalidate active sessions and preauth keys.
      • Check your reporting obligations: For confirmed access, prepare the NIS2 early warning to BSI or your national CSIRT within 24 h. Also assess GDPR Art. 33 notification if mailbox content was accessible.

    2. Runbook step 2

      Mitigation layers

      • Configuration: Verify that pax is actually in use. Remove cpio from the amavis process $PATH, or chmod 750 it so the zimbra user cannot execute it. Document the change so package updates do not silently revert it.
      • Email gateway: Configure the upstream secure email gateway to quarantine or reject inbound .cpio, .tar, and .rpm archive attachments from external senders. The exploit is triggered by a crafted archive delivered by email, with no authentication required.
      • Filesystem hardening: Put /opt/zimbra/jetty/webapps/zimbra/public/ under file-integrity monitoring (AIDE, Wazuh, Tripwire). Where operationally feasible, remove the amavis context's write access to the Jetty webroot.
      • Network segmentation: Expose the Zimbra web UI (443/tcp) only through a reverse proxy or VPN. Never expose the admin console (7071/tcp) to the internet. Restrict the mail server's outbound connections to required destinations with egress filtering.
      • WAF / reverse proxy: Block requests for *.jsp under /public/, except for an explicit allowlist of legitimate Zimbra files (e.g. login.jsp). Alert on any unknown JSP path being requested.

    3. Runbook step 3

      Detection rules

      • Web access logs (/opt/zimbra/log/access_log.*, nginx proxy logs): Look for requests to undocumented JSP files under /public/. Example SPL: index=zimbra sourcetype=access_combined uri_path="/public/*.jsp" NOT uri_path IN ("/public/login.jsp","/public/error.jsp") | stats count by src_ip, uri_path.
      • auditd: Watch the webroot with -w /opt/zimbra/jetty/webapps/zimbra/public/ -p wa -k zimbra_webroot. Treat any file creation whose exe is cpio or a process under amavis as high-fidelity.
      • EDR process ancestry: java (Jetty, user zimbra) spawning sh, bash, curl, wget, python, or nc is the classic webshell pattern. Sigma shape: ParentImage|endswith: '/java' AND User: 'zimbra' AND Image|endswith: ['/sh','/bash','/curl','/wget'].
      • amavis / MTA logs (/var/log/zimbra.log): Look for inbound mail with .cpio or .tar attachments whose extraction produces errors or path-traversal artefacts (../, symlinks). Correlate with new files appearing in the webroot within minutes.
      • Network (Zeek/Suricata): Watch for anomalous outbound connections from the mail server and bursts of HTTP POSTs to a single JSP endpoint (webshell interaction). Also hunt for bulk mailbox export via SOAP/REST (/service/home/*?fmt=tgz).

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    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.

    Source: CSA/SingCERT, cvelistv5, NVD (NIST), CISA KEV Catalog, CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    synacorzimbra_collaboration_suite
    • 9.0.0
    • 8.8.15
    • —
    • —

    Vendors and products

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    CSA/SingCERTActive Exploitation of Critical Vulnerability in Zimbra Collaboration Suite (opens in a new tab)CSA/SingCERTactively exploited
    ANSSI / CERT-FRLicence Ouverte 2.0, as of CERTFR-2022-ALE-009 – [MaJ] Vulnérabilité dans Zimbra Collaboration (clôturée 2023-03-14) (opens in a new tab)cert.cyber.gouv.fractively exploited
    Packet StormZimbra Collaboration Suite TAR Path Traversal (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—

    References & sources

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedMITRE

      Show 15 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      http://packetstormsecurity.com/files/169458/Zimbra-Collaboration-Suite-TAR-Path-Traversal.html
      Referenceadded
      —
      https://forums.zimbra.org/viewtopic.php?t=71153&p=306532
      Referenceadded
      —
      https://wiki.zimbra.com/wiki/Security_Center
      Referenceadded
      —
      https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
      Referenceadded
      —
      https://www.secpod.com/blog/unpatched-rce-bug-in-zimbra-collaboration-suite-exploited-in-wild/
      Referenceremoved
      http://packetstormsecurity.com/files/169458/Zimbra-Collaboration-Suite-TAR-Path-Traversal.html
      —
      Referenceremoved
      https://forums.zimbra.org/viewtopic.php?t=71153&p=306532
      —
      Referenceremoved
      https://wiki.zimbra.com/wiki/Security_Center
      —
      Referenceremoved
      https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
      —
      Referenceremoved
      https://www.secpod.com/blog/unpatched-rce-bug-in-zimbra-collaboration-suite-exploited-in-wild/
      —
      Reference typeremoved
      http://packetstormsecurity.com/files/169458/Zimbra-Collaboration-Suite-TAR-Path-Traversal.html Types: Exploit, Third Party Advisory, VDB Entry
      —
      Reference typeremoved
      https://forums.zimbra.org/viewtopic.php?t=71153&p=306532 Types: Mitigation, Vendor Advisory
      —
      Reference typeremoved
      https://wiki.zimbra.com/wiki/Security_Center Types: Patch, Release Notes, Vendor Advisory
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      Reference typeremoved
      https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories Types: Vendor Advisory
      —
      Reference typeremoved
      https://www.secpod.com/blog/unpatched-rce-bug-in-zimbra-collaboration-suite-exploited-in-wild/ Types: Third Party Advisory
      —

      Source identifier: cve@mitre.org

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: active, automatable: yes

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-41352
      Referenceremoved
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-41352
      —
      Reference typeremoved
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-41352 Types: US Government Resource
      —
      SSVC assessmentchanged
      {"id":"CVE-2022-41352","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2025-02-03T14:33:44.078384Z"}
      {"id":"CVE-2022-41352","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2022-10-07T00:00:00+00:00"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    3. Record modifiedCVE Program

      Show 15 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      http://packetstormsecurity.com/files/169458/Zimbra-Collaboration-Suite-TAR-Path-Traversal.html
      Referenceadded
      —
      https://forums.zimbra.org/viewtopic.php?t=71153&p=306532
      Referenceadded
      —
      https://wiki.zimbra.com/wiki/Security_Center
      Referenceadded
      —
      https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
      Referenceadded
      —
      https://www.secpod.com/blog/unpatched-rce-bug-in-zimbra-collaboration-suite-exploited-in-wild/
      Referenceremoved
      http://packetstormsecurity.com/files/169458/Zimbra-Collaboration-Suite-TAR-Path-Traversal.html
      —
      Referenceremoved
      https://forums.zimbra.org/viewtopic.php?t=71153&p=306532
      —
      Referenceremoved
      https://wiki.zimbra.com/wiki/Security_Center
      —
      Referenceremoved
      https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
      —
      Referenceremoved
      https://www.secpod.com/blog/unpatched-rce-bug-in-zimbra-collaboration-suite-exploited-in-wild/
      —
      Reference typeremoved
      http://packetstormsecurity.com/files/169458/Zimbra-Collaboration-Suite-TAR-Path-Traversal.html Types: Exploit, Third Party Advisory, VDB Entry
      —
      Reference typeremoved
      https://forums.zimbra.org/viewtopic.php?t=71153&p=306532 Types: Mitigation, Vendor Advisory
      —
      Reference typeremoved
      https://wiki.zimbra.com/wiki/Security_Center Types: Patch, Release Notes, Vendor Advisory
      —
      Reference typeremoved
      https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories Types: Vendor Advisory
      —
      Reference typeremoved
      https://www.secpod.com/blog/unpatched-rce-bug-in-zimbra-collaboration-suite-exploited-in-wild/ Types: Third Party Advisory
      —

      Source identifier: af854a3a-2127-422b-91ae-364da2661108

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