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CVE-2026-102489: Zammad GmbH Zammad Security Vulnerability (CVSS 9.4)

CVE-2026-102489 is a critical severity security vulnerability in Zammad GmbH Zammad with a CVSS score of 9.4. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

Last updated: Oct 10, 2026

Quick answer

Direct answer

CVE-2026-102489 is a critical severity security vulnerability in Zammad GmbH Zammad with a CVSS score of 9.4. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

Read our full CVE Watch analysis of CVE-2026-102489

Risk scores

CVSS base score
9.4CRITICAL
EPSS probability
1.26%
Higher than 69 percent of all CVEs
CISA KEV
Exploited Yes
Added Oct 2, 2026
CVSS metricWhat it means
Attack vector (AV:N)Network: reachable remotely
Attack complexity (AC:L)Low complexity
Attack requirements (AT:N)No attack requirements
Privileges required (PR:N)No privileges required
User interaction (UI:P)Passive user interaction
Confidentiality (VC:H)High confidentiality impact
Integrity (VI:H)High integrity impact
Availability (VA:H)High availability impact

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:X/V:C/RE:X/U:X

CISA required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

About Zammad GmbH Zammad

CVE-2026-102489 affects Zammad GmbH Zammad, a product from Zammad GmbH. Before acting, confirm where Zammad GmbH Zammad runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: Zammad versions 6.3.0 to 6.5.4 are vulnerable a session hijack vulnerability that leads to remote code execution as the zammad user. The bug is also present in version 7.0.0 to version 7.1.2, but not exploitable due to changes in the underlying framework.

Based on its CVSS vector, the flaw can be reached over the network, needs no login, and relies on a user taking an action. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

Affected versions and timeline

FieldDetail
ProductZammad GmbH Zammad
Affected versionsZammad from 6.3.0 up to and including 6.5.4
PublishedSep 30, 2026
Last modifiedOct 10, 2026
Added to CISA KEVOct 2, 2026
Assigning CNAcsirt@divd.nl

How to detect it

  • Inventory every instance of Zammad GmbH Zammad and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Zammad GmbH Zammad named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Zammad GmbH Zammad to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeKnown exploited, so top priority.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-102489 is a critical severity security vulnerability in Zammad GmbH Zammad with a CVSS score of 9.4. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.

Related CVEs

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Zammad packages built with packager.io (DEB and RPM) could have allowed a local attacker who already had file system write privileges as the unprivileged zammad service account to escalate to full root privileges on the host. Service processes began running as root and executed files that were owned and writable by the zammad account before dropping their identity to that account. An attacker holding that foothold could have escalated within seconds, because the affected services were restarted automatically whenever they stopped; no administrator interaction was required. Only installations from the DEB and RPM packages were affected — installations from source or the official container images were not. All released packaged versions were affected.

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All Zammad GmbH CVEs in 2026
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