Synacor Zimbra Collaboration Suite (ZCS) Arbitrary File Upload Vulnerability
Synacor · Zimbra Collaboration Suite (ZCS)
Zimbra Collaboration Suite (ZCS) versions 8.8.15 and 9.0 contain an arbitrary file upload flaw in the amavis component, where extraction via the cpio utility can write files into the /opt/zimbra/jetty/webapps/zimbra/public directory. An attacker who can send mail through this path can place arbitrary files there, which can lead to unauthorised access to other user accounts, with no authentication or user interaction required.
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.
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 2/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 24 days after disclosure. Public exploit code (Metasploit) was available 3 months before disclosure.
- Public exploit codeMetasploit3 mo before
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidenceAdded to CISA KEVknown ransomware use; EU database agrees+24 days
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order, 2 cited passages 2Initial AccessTA0001
Unauthenticated file upload to public-facing mail server
An attacker can upload arbitrary files through amavis via a cpio loophole
PersistenceTA0003
Writes web shell into public webapp directory
extraction to /opt/zimbra/jetty/webapps/zimbra/public
Detection
0 rules for this CVE · 184 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2022-41352 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Exploit Public-Facing ApplicationT1190149 general rules
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- Confluence Exploitation CVE-2019-3398criticaltest
- CVE-2010-5278 Exploitation Attemptcriticaltest
- CVE-2020-0688 Exchange Exploitation via Web Logcriticaltest
- CVE-2020-10148 SolarWinds Orion API Auth Bypasscriticaltest
- CVE-2020-5902 F5 BIG-IP Exploitation Attemptcriticaltest
Web ShellT1505.00335 general rules
- Certificate Request Export to Exchange Webservercriticaltest
- CVE-2021-40539 Zoho ManageEngine ADSelfService Plus Exploitcriticaltest
- Mailbox Export to Exchange Webservercriticaltest
- Oracle WebLogic Exploitcriticaltest
- Solarwinds SUPERNOVA Webshell Accesscriticaltest
- Webshell Remote Command Executioncriticaltest
- WordPress Wp2shell Webshell Plugin Accesscriticalexperimental
- Antivirus - Web Shell Detection Signaturehightest
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- Actively_Exploited_Kev | Oct 22, 202621 Oct 2026
- 44 more on OTX