How severe is CVE-2026-33368?

CVE-2026-33368 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-33368 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33368?

CVE-2026-33368 affects Synacor Zimbra Collaboration Suite. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33368?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-33368 have an EU (EUVD) identifier?

Yes. CVE-2026-33368 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13690.

When was CVE-2026-33368 published?

CVE-2026-33368 was published on 2026-03-20 and last updated on 2026-06-17.

CVE-2026-33368

CVE-2026-33368 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-13690
Weakness: CWE-79
Affected product: Synacor Zimbra Collaboration Suite
Published: 2026-03-20
Last modified: 2026-06-17

Description

Zimbra Collaboration Suite (ZCS) 10.0 and 10.1 contains a reflected cross-site scripting (XSS) vulnerability in the Classic Webmail REST interface (/h/rest). The application fails to properly sanitize user-supplied input, allowing an unauthenticated attacker to inject malicious JavaScript into a crafted URL. When a victim user accesses the link, the injected script executes in the context of the Zimbra webmail application, which could allow the attacker to perform actions on behalf of the victim.

Frequently asked questions

What is CVE-2026-33368?: Zimbra Collaboration Suite (ZCS) 10.0 and 10.1 contains a reflected cross-site scripting (XSS) vulnerability in the Classic Webmail REST interface (/h/rest). The application fails to properly sanitize user-supplied input, allowing an unauthenticated attacker to inject malicious JavaScript into a crafted URL. When a victim user accesses the link, the injected script executes in the context of the Zimbra webmail application, which could allow the attacker to perform actions on behalf of the victim.
How severe is CVE-2026-33368?: CVE-2026-33368 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-33368 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33368?: CVE-2026-33368 affects Synacor Zimbra Collaboration Suite. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33368?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-33368 have an EU (EUVD) identifier?: Yes. CVE-2026-33368 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13690.
When was CVE-2026-33368 published?: CVE-2026-33368 was published on 2026-03-20 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*

More vulnerabilities in Synacor Zimbra Collaboration Suite

CVE-2024-45519 — Critical (CVSS 10.0): The postjournal service in Zimbra Collaboration (ZCS) before 8.8.15 Patch 46, 9 before 9.0.0 Patch 41, 10 before…
CVE-2022-41352 — Critical (CVSS 9.8): An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0. An attacker can upload arbitrary files through…
CVE-2022-37042 — Critical (CVSS 9.8): Zimbra Collaboration Suite (ZCS) 8.8.15 and 9.0 has mboximport functionality that receives a ZIP archive and extracts…
CVE-2020-7796 — Critical (CVSS 9.8): Zimbra Collaboration Suite (ZCS) before 8.8.15 Patch 7 allows SSRF when WebEx zimlet is installed and zimlet JSP is…
CVE-2019-9670 — Critical (CVSS 9.8): mailboxd component in Synacor Zimbra Collaboration Suite 8.7.x before 8.7.11p10 has an XML External Entity injection…
CVE-2019-6980 — Critical (CVSS 9.8): Synacor Zimbra Collaboration Suite 8.7.x through 8.8.11 allows insecure object deserialization in the IMAP component.

All CVEs affecting Synacor Zimbra Collaboration Suite →

Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities

CVE-2025-49410 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Imran Emu TC…
CVE-2024-47875 — Critical (CVSS 10.0): DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. DOMpurify was vulnerable to…
CVE-2024-6886 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Gitea…
CVE-2023-45144 — Critical (CVSS 10.0): com.xwiki.identity-oauth:identity-oauth-ui is a package to aid in building identity and service providers based on…
CVE-2023-45138 — Critical (CVSS 10.0): Change Request is an pplication allowing users to request changes on a wiki without publishing the changes directly.…
CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…

Browse all CWE-79 (Cross-site Scripting (XSS)) vulnerabilities →