CVE-2022-24682
Synacor Zimbra Collaborate Suite (ZCS) Cross-Site Scripting Vulnerability
Description
CVE-2022-24682 is a MEDIUM improper encoding or escaping of output vulnerability affecting Synacor Zimbra Collaborate Suite (ZCS), carrying a CVSS 3.1 score of 6.1. Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting (XSS) vulnerability in the Calendar feature that allows an attacker to execute arbitrary code. Affected products include Synacor Zimbra Collaboration Suite (>= 8.8.0, < 8.8.15; 8.8.15). This CVE is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog with a remediation deadline of 2022-03-11. CISA's KEV catalog confirms ransomware association for this vulnerability. With an EPSS score of 0.87968 (99.48th percentile), this vulnerability demonstrates significant real-world exploitation activity and should be prioritized for immediate remediation.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NOpen in CalculatorCWEs
Affected Products
| Vendor | Product | Version |
|---|---|---|
| synacor | zimbra collaboration suite | >= 8.8.0, < 8.8.15; 8.8.15 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
References
- https://blog.zimbra.com/2022/02/hotfix-available-5-feb-for-zero-day-exploit-vulnerability-in-zimbra-8-8-15/(Vendor Advisory)
- https://wiki.zimbra.com/wiki/Security_Center(Vendor Advisory)
- https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P30(Release Notes, Vendor Advisory)
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories(Vendor Advisory)
- https://www.volexity.com/blog/2022/02/03/operation-emailthief-active-exploitation-of-zero-day-xss-vulnerability-in-zimbra/(Exploit, Third Party Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-24682(US Government Resource)
Weakness Type
CWE-116: Improper Encoding or Escaping of Output
CVE-2022-24682 is classified under CWE-116 — Improper Encoding or Escaping of Output. Improper Encoding or Escaping of Output occurs when software prepares a structured message for communication with another component but does not properly encode or escape the data, allowing attackers to modify the structure of the message. This is the root cause of many injection vulnerabilities. The specific encoding required depends on the output context: HTML encoding for web pages, SQL escaping for database queries, shell escaping for command execution, URL encoding for URLs, and LDAP encoding for directory queries. Using the wrong encoding or no encoding enables injection attacks.
In the context of Synacor Zimbra Collaborate Suite (ZCS), this weakness is particularly concerning because Improper output encoding is fundamental to injection vulnerabilities across all contexts. Cross-Site Scripting (XSS) results from improper HTML/JavaScript encoding. SQL Injection stems from improper SQL encoding. Organizations using affected versions should understand that this vulnerability class has historically enabled severe compromises across enterprise environments.
Impact Analysis
CVE-2022-24682 carries a CVSS 3.1 score of 6.1 (MEDIUM) with Changed Scope.
Confidentiality (LOW): Limited confidential information may be exposed through exploitation, though the scope of data leakage is constrained.
Integrity (LOW): Some modification of data or system state is possible, though the extent of integrity impact is limited.
Availability (NONE): Availability impact is minimal for this vulnerability.
Scope Changed: The vulnerability's scope is Changed (C), meaning exploitation can affect resources beyond the vulnerable component itself. This extends the potential blast radius significantly, as compromising Synacor Zimbra Collaborate Suite (ZCS) may provide a foothold to attack other connected systems and resources.
With an EPSS score of 0.87968 (99.48th percentile), this vulnerability ranks among the most likely to be exploited in real-world attacks, underscoring the urgency of remediation.
Exploit Maturity
CVE-2022-24682 has confirmed active exploitation in the wild and is listed in CISA's Known Exploited Vulnerabilities catalog.
Exploit status: This vulnerability has been actively exploited, as confirmed by its inclusion in the KEV catalog. The EPSS score of 0.87968 (99.48th percentile) places it among the most exploited vulnerabilities tracked.
Ransomware association: CISA's KEV catalog confirms a known association between CVE-2022-24682 and ransomware campaigns. Threat actors have leveraged this vulnerability as part of ransomware attack chains for initial access or lateral movement.
Public exploits: Exploit code is publicly available, including references at www.volexity.com. The availability of public exploit code significantly lowers the barrier to exploitation.
KEV deadline: CISA required federal agencies to remediate this vulnerability by 2022-03-11. All organizations should treat this deadline as a strong recommendation for their own remediation timelines.
Remediation
- Apply vendor patches immediately. Apply updates per vendor instructions. Consult the vendor advisory at blog.zimbra.com for specific patch guidance.
- Verify affected product versions in your environment. Identify all instances of Synacor Zimbra Collaborate Suite (ZCS) in your infrastructure (affected versions: Synacor Zimbra Collaboration Suite (>= 8.8.0, < 8.8.15; 8.8.15)). Use asset inventory and vulnerability scanning tools to ensure no instances are missed.
- Implement interim mitigations if patching is delayed. If immediate patching is not feasible, apply network-level controls such as restricting access to the affected component, enabling enhanced logging, and monitoring for indicators of compromise.
- Scan for signs of prior exploitation. Given the confirmed active exploitation of this vulnerability, review system logs and security monitoring data for evidence of compromise. Conduct a thorough investigation if any suspicious activity is detected.
- Update detection signatures and monitoring rules. Ensure intrusion detection and prevention systems, endpoint detection tools, and SIEM rules are updated to detect exploitation attempts targeting CVE-2022-24682.
- Conduct a post-remediation review. After patching, verify the fix is effective and document the remediation actions taken. Update your vulnerability management records and assess whether any additional hardening measures are warranted.
Technical Details
CVE-2022-24682 is a MEDIUM-severity vulnerability in Synacor Zimbra Collaborate Suite (ZCS) that can be exploited remotely over the network without physical access. The attack complexity is low, meaning no specialized conditions or preparation are required beyond the attack prerequisites. No prior authentication or privileges are needed to initiate the attack. User interaction is required, meaning a victim must perform an action such as opening a file, clicking a link, or visiting a website for exploitation to succeed.
Technical mechanism: Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting (XSS) vulnerability in the Calendar feature that allows an attacker to execute arbitrary code. The underlying flaw relates to improper encoding or escaping of output, where Improper Encoding or Escaping of Output occurs when software prepares a structured message for communication with another component but does not properly encode or escape the data, allowing attackers to modify the structure of the message. This is the root cause of many injection vulnerabilities.
CVSS 3.1 vector analysis: The vector reflects an Attack Vector of NETWORK, Attack Complexity of LOW, Privileges Required of NONE, User Interaction of REQUIRED, Scope CHANGED, and impact ratings of LOW/LOW/NONE for Confidentiality/Integrity/Availability respectively. The Changed scope indicates that exploitation can cascade beyond the initially compromised component.
Frequently Asked Questions
What is CVE-2022-24682?
CVE-2022-24682 is a MEDIUM-severity vulnerability (CVSS 6.1) in Synacor Zimbra Collaborate Suite (ZCS) that synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting (XSS) vulnerability in the Calendar feature that allows an attacker to execute arbitrary code. It is listed in CISA's Known Exploited Vulnerabilities catalog, confirming real-world exploitation. This vulnerability has been associated with ransomware campaigns.
Which products are affected by CVE-2022-24682?
The affected products include Synacor Zimbra Collaboration Suite (>= 8.8.0, < 8.8.15; 8.8.15). Organizations running any of these versions should verify their exposure and prioritize remediation. Check vendor advisories for the complete and most current list of affected versions.
How do I fix CVE-2022-24682?
Apply updates per vendor instructions. Ensure all affected instances of Synacor Zimbra Collaborate Suite (ZCS) are identified using vulnerability scanning and asset management tools. If immediate patching is not possible, implement network-level mitigations and enhanced monitoring. After patching, verify the fix and scan for indicators of prior compromise.
How severe is CVE-2022-24682?
CVE-2022-24682 is rated MEDIUM with a CVSS 3.1 score of 6.1. Its EPSS score of 0.87968 places it in the 99.48th percentile for exploitation likelihood. The vulnerability has confirmed active exploitation in the wild and is associated with ransomware campaigns, was required to be remediated by federal agencies by 2022-03-11 per CISA's KEV directive.
Need Help With Vulnerability Management?
Our security experts can help you prioritize and remediate vulnerabilities effectively.