CVE-2026-33373: An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1

Routine

HIGH 8.8UPGRADE

CVE-2026-33373 is a high-severity flaw (CVSS 8.8) affecting zimbra collaboration suite. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1. A Cross-Site Request Forgery (CSRF) vulnerability exists in Zimbra Web Client due to the issuance of authentication tokens without CSRF protection during certain account state transitions. Specifically, tokens generated after operations such as enabling two-factor authentication or changing a password may lack CSRF enforcement. While such a token is active, authenticated SOAP re

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 89%)
CISA exploited list	No
Weakness	CWE-352
Published	2026-03-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: synacor

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-30 15:16 UTCPublished CVE record published
2026-06-17 10:37 UTCUpdated Record last modified

synacor zimbra collaboration suite UPGRADE

Affected: >= 10.0.0 and < 10.0.18 · >= 10.1.0 and < 10.1.13

Fixed in: 10.0.18, 10.1.13

Safe to downgrade to: a release before 10.0.0

1. Check installed version

apt-cache policy zimbra-collaboration-suite || rpm -q zimbra-collaboration-suite || zimbra-collaboration-suite --version

2. UPGRADE to 10.0.18 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade zimbra-collaboration-suite

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade zimbra-collaboration-suite

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 10.0.0 (Debian / Ubuntu)

apt-cache madison zimbra-collaboration-suite sudo apt install zimbra-collaboration-suite=<VERSION_BEFORE_10.0.0> sudo apt-mark hold zimbra-collaboration-suite

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list zimbra-collaboration-suite sudo dnf downgrade zimbra-collaboration-suite-<VERSION_BEFORE_10.0.0> sudo dnf versionlock add zimbra-collaboration-suite

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-33373?

zimbra collaboration suite: upgrade to 10.0.18, 10.1.13. Exact commands for each OS are on this page.

Is CVE-2026-33373 being exploited?

CVE-2026-33373 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-33373 affect?

CVE-2026-33373 affects zimbra collaboration suite. Severity is high (CVSS 8.8). An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1. A Cross-Site Request Forgery (CSRF) vulnerability exists in Zimbra Web Client due to the issuance of authentication tokens without CSRF protection during certain account s

How urgent is CVE-2026-33373?

Priority 34/100. High severity

Software pages

Zimbra vulnerabilities

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References

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