CVE-2026-102489: Zammad GmbH Zammad Session Fixation Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Zammad GmbH Zammad. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-10-02, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-10-05; treat that as the outer limit, not the target.
• EPSS 1.3%, percentile 69: FIRST’s model estimates a 1.3% chance of exploitation activity in the next 30 days, higher than 69% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Editorial verdict: Act now. Zammad CVE-2026-102489/102490: Exploited RCE-to-Root Chain — Self-hosted Zammad on 6.x is remotely exploitable and was used in a real breach: upgrade to 7.2.2 today (6.5.5 only as a stopgap), and patch DEB/RPM installs of any version to close the root escalation.

What it is

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.

CISA’s summary

Zammad GmbH Zammad contains a session fixation vulnerability that can lead to remote code execution as the zammad user. This vulnerability can be chained with CVE-2026-102490.

Weakness type: CWE-384.

Product: Zammad GmbH Zammad · Assigned by: DIVD · Published: 2026-09-30

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: passive

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-10-02; federal due date 2026-10-05. Known ransomware use: Unknown.
• 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.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.26% probability of exploitation activity in the next 30 days; percentile 69.

Timeline

• 2026-09-30 — CVE record published by DIVD
• 2026-09-30 — erroneo.us brief: Zammad CVE-2026-102489/102490: Exploited RCE-to-Root Chain
• 2026-10-02 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-10-05 — CISA remediation deadline for US federal agencies
• 2026-10-19 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. zammad.com zammad.com
2. Listed in CISA KEV notes (zammad.com) zammad.com
3. Listed in CISA KEV notes (community.zammad.org) community.zammad.org

Vulnerability records

1. CVE.org record CVE-2026-102489 cve.org
2. NVD entry CVE-2026-102489 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov
2. Listed in CISA KEV notes (cisa.gov) cisa.gov
3. Listed in CISA KEV notes (cisa.gov) cisa.gov

Other references from the CVE record and advisory

1. csirt.divd.nl csirt.divd.nl
2. csirt.divd.nl csirt.divd.nl

All exploited Zammad GmbH vulnerabilities · Today’s Security Digest