CVE-2025-27915
Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability - [Actively Exploited]
Description
An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a <details> tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.
INFO
Published Date :
March 12, 2025, 3:15 p.m.
Last Modified :
Oct. 21, 2025, 11:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CISA KEV (Known Exploited Vulnerabilities)
For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.
Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
https://wiki.zimbra.com/wiki/Security_Center ; https://nvd.nist.gov/vuln/detail/CVE-2025-27915
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Sanitize HTML content in ICS files.
- Update affected Zimbra Collaboration versions.
- Validate user input for ICS processing.
- Avoid rendering untrusted HTML directly.
Public PoC/Exploit Available at Github
CVE-2025-27915 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-27915.
| URL | Resource |
|---|---|
| https://wiki.zimbra.com/wiki/Security_Center | Release Notes |
| https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13#Security_Fixes | Release Notes |
| https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5#Security_Fixes | Release Notes |
| https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P44#Security_Fixes | Release Notes |
| https://strikeready.com/blog/0day-ics-attack-in-the-wild/ | Exploit Third Party Advisory |
| https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-27915 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-27915
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Main repo about patched Zimbra repos
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-27915 vulnerability anywhere in the article.
-
Daily CyberSecurity
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ISC Patches High-Severity Kea DHCPv4 DoS (CVE-2025-11232) Flaw, Allows Crash via Malformed Hostname
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Wordfence Warns of Active Exploits Targeting Critical Privilege Escalation Flaw in WP Freeio (CVE-2025-11533)
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Daily CyberSecurity
Researcher Details Critical Authentication Bypasses in WSO2 API Manager and Identity Server
Security researcher Crnkovic has disclosed three critical vulnerabilities — CVE-2025-9152, CVE-2025-10611, and CVE-2025-9804 — in WSO2 API Manager and WSO2 Identity Server, each scoring 9.8 on the CVS ... Read more
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TEE.fail: Researchers Break Intel SGX/TDX and AMD SEV-SNP with Sub-$1,000 DDR5 Memory Bus Attack
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Researcher Details Windows Cloud Files Mini Filter Driver Elevation of Privilege Flaw (CVE-2025-55680)
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Daily CyberSecurity
LiteSpeed Cache Flaw (CVE-2025-12450): 7 Million WordPress Sites Exposed to XSS Attack
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CISA KEV Alert: Critical DELMIA Apriso Flaws Under Active Exploitation Allow RCE and Privileged Access
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Critical IBM Maximo Flaw (CVE-2025-36386, CVSS 9.8) Allows Unauthenticated Bypass to Cognos Analytics
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Daily CyberSecurity
Docker Compose Path Traversal (CVE-2025-62725) Allows Arbitrary File Overwrite via OCI Artifacts
The Docker Compose project has disclosed a high-severity path traversal vulnerability tracked as CVE-2025-62725 (CVSS v4 8.9), which affects users across Docker Desktop, standalone Compose binaries, C ... Read more
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Daily CyberSecurity
Wear OS Messages Flaw (CVE-2025-12080) Allows Unprivileged Apps to Send SMS/RCS Without Permission, PoC Available
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Critical Magento Flaw (CVE-2025-54236) Actively Exploited for Session Hijacking and Unauthenticated RCE
The Akamai Security Intelligence Group has issued an urgent warning after observing active exploitation in the wild of a newly disclosed Magento vulnerability known as SessionReaper (CVE-2025-54236). ... Read more
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Daily CyberSecurity
Critical MikroTik Flaw (CVE-2025-61481, CVSS 10.0) Exposes Router Admin Credentials Over Unencrypted HTTP WebFig
A newly disclosed vulnerability, CVE-2025-61481, rated a maximum CVSS score of 10.0, affects MikroTik RouterOS (v7.14.2) and SwitchOS (v2.18) and allows remote attackers to execute arbitrary code or i ... Read more
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Daily CyberSecurity
Critical .NET Flaw (CVE-2025-55315) in QNAP: NAS Backup Utility Vulnerable to Credential Theft
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Daily CyberSecurity
Microsoft Teams Will Auto-Track Office Location via Wi-Fi
Microsoft’s collaborative workspace platform Microsoft Teams, widely used by enterprises and professional teams, is set to receive a notable new feature this December, according to the latest roadmap ... Read more
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Daily CyberSecurity
Values Over Cash: Python Foundation Rejects $1.5M US Grant Over Anti-DEI Clause
In January 2025, the Python Software Foundation (PSF) submitted a proposal to the U.S. National Science Foundation (NSF) under the Open Source Ecosystem Security, Safety, and Privacy initiative, aimin ... Read more
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Daily CyberSecurity
Kaspersky Exposes Chrome Zero-Day RCE (CVE-2025-2783) Delivering Memento Labs Spyware in ForumTroll Campaign
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Daily CyberSecurity
High-Severity OpenVPN Flaw (CVE-2025-10680) Allows Script Injection on Linux/macOS via Malicious DNS Server
Security researchers have disclosed a high-severity vulnerability, tracked as CVE-2025-10680 (CVSS 8.8), affecting OpenVPN 2.7_alpha1 through 2.7_beta1 releases. The flaw exposes Unix-like systems to ... Read more
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Daily CyberSecurity
SideWinder APT Shifts to PDF/ClickOnce Chain to Target South Asian Diplomacy with StealerBot
Trellix Advanced Research Center (ARC) has exposed a sophisticated espionage campaign conducted by the SideWinder APT group, targeting multiple South Asian diplomatic entities — including embassies an ... Read more
The following table lists the changes that have been made to the
CVE-2025-27915 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 21, 2025
Action Type Old Value New Value Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 21, 2025
Action Type Old Value New Value Removed Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 21, 2025
Action Type Old Value New Value Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915 -
Modified Analysis by [email protected]
Oct. 08, 2025
Action Type Old Value New Value Added Reference Type CISA-ADP: https://strikeready.com/blog/0day-ics-attack-in-the-wild/ Types: Exploit, Third Party Advisory -
CVE CISA KEV Update by 9119a7d8-5eab-497f-8521-727c672e3725
Oct. 08, 2025
Action Type Old Value New Value Added Date Added 2025-10-07 Added Due Date 2025-10-28 Added Required Action Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Added Vulnerability Name Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 07, 2025
Action Type Old Value New Value Added Reference https://strikeready.com/blog/0day-ics-attack-in-the-wild/ -
Initial Analysis by [email protected]
Apr. 02, 2025
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:zimbra:collaboration:9.0.0:-:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p2:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p3:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p4:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p5:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p6:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p9:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p0:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p1:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p10:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p11:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p12:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p13:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p14:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p15:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p19:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p7:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p8:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p16:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p20:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p21:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p23:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p24:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p24.1:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p25:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p26:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p27:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p28:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p29:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p30:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p31:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p32:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p33:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p34:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p35:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p36:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p37:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p38:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p39:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p40:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p7.1:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:*:*:*:*:*:*:*:* versions from (including) 10.0.0 up to (excluding) 10.0.13 *cpe:2.3:a:zimbra:collaboration:9.0.0:p41:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p42:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:9.0.0:p43:*:*:*:*:*:* *cpe:2.3:a:zimbra:collaboration:*:*:*:*:*:*:*:* versions from (including) 10.1.0 up to (excluding) 10.1.5 Added Reference Type MITRE: https://wiki.zimbra.com/wiki/Security_Center Types: Release Notes Added Reference Type MITRE: https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13#Security_Fixes Types: Release Notes Added Reference Type MITRE: https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5#Security_Fixes Types: Release Notes Added Reference Type MITRE: https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P44#Security_Fixes Types: Release Notes -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Mar. 12, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Added CWE CWE-79 -
New CVE Received by [email protected]
Mar. 12, 2025
Action Type Old Value New Value Added Description An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a <details> tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration. Added Reference https://wiki.zimbra.com/wiki/Security_Center Added Reference https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13#Security_Fixes Added Reference https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5#Security_Fixes Added Reference https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P44#Security_Fixes