Google security researchers have discovered a Zimbra zero-day vulnerability that has been exploited in the wild. Users are being advised to manually patch their installations.
Exploitation of the zero-day affecting the popular email and collaboration solution was discovered by Clement Lecigne from Google’s Threat Analysis Group (TAG).
A security update that includes a patch for the vulnerability is expected to be released later this month. In the meantime, users can manually apply mitigations provided by Zimbra.
The vulnerability appears to be a cross-site scripting (XSS) bug impacting Zimbra Collaboration Suite 8.8.15. Exploitation of these types of flaws, which can be leveraged for remote code execution, typically requires user interaction.
Zimbra developers noted that the flaw “could potentially impact the confidentiality and integrity of your data”, but their advisory does not explicitly say that the vulnerability has been exploited in the wild. Attackers often exploit Zimbra vulnerabilities to gain access to email servers.
A CVE identifier has yet to be assigned to the vulnerability.
It’s not uncommon for Zimbra vulnerabilities to be exploited in the wild, including XSS flaws. In some cases, Zimbra weaknesses have been exploited to hack more than 1,000 email servers.
According to Zimbra’s website, more than 200,000 organizations across 140 countries use its product for email and collaboration.
CISA’s Known Exploited Vulnerabilities Catalog currently includes eight Zimbra flaws, but the cybersecurity agency has yet to add the latest zero-day.
Related: Zimbra Flaw Exploited by Russia Against NATO Countries Added to CISA ‘Must Patch’ List
Related: Critical Zimbra RCE Vulnerability Exploited in Attacks
Related: UnRAR Vulnerability Exploited in the Wild, Likely Against Zimbra Servers

Eduard Kovacs (@EduardKovacs) is a managing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.
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