CVE-2026-102489

Zammad GmbH Zammad Session Fixation Vulnerability

Actively exploited (CISA KEV) Critical 9.8 CVSS 3.1

Description

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 vulnerability is also present in version 7.0.0 to version 7.1.3, but not exploitable due to environment conditions.

Description as published by the source, in English.

Key facts

Published: 2026-09-30
Last modified: 2026-10-03
Assigned by: csirt@divd.nl
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Scored by: nvd@nist.gov (NVD Primary)
Fix available: Not registered in the sources

Actively exploited

CISA added this vulnerability to the Known Exploited Vulnerabilities catalogue on 2026-10-02, with a remediation deadline of 2026-10-05 for US federal agencies.

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.

Affected products

Vendor	Product	Versions	Status
Docker	Docker	all versions listed	Not affected
Linux	Linux Kernel	all versions listed	Not affected
Zammad	Zammad	≥ 6.3.0, < 6.5.4	Affected
Zammad	Zammad	≥ 7.0.0, ≤ 7.1.3	Affected

Weakness type

CWE-384: Session Fixation
Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.

Attack techniques

Derived through the weakness type: CVE to CWE to CAPEC to ATT&CK. This shows which techniques the weakness class is historically used for. It does not assert that this vulnerability has been exploited that way.

T1134: Access Token Manipulation stealth, privilege-escalation
T1134.001: Token Impersonation/Theft stealth, privilege-escalation
T1134.002: Create Process with Token stealth, privilege-escalation
T1134.003: Make and Impersonate Token stealth, privilege-escalation
T1528: Steal Application Access Token credential-access
T1539: Steal Web Session Cookie credential-access
T1550.004: Web Session Cookie lateral-movement
T1606: Forge Web Credentials credential-access

References

https://csirt.divd.nl/CVE-2026-102489 Third Party Advisory
https://csirt.divd.nl/DIVD-2026-00015 Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-102489 US Government Resource

Related at Berigo

Articles

Nine vulnerabilities entered the exploited catalogue in two days Same product 2026-09-01
CISA catalogued three more vulnerabilities on 27 August 2026, a day after six others went in. The three cover ownCloud, the Linux kernel and JFrog Ar…
Five of the six new KEV entries date from 2015 to 2022 Same product 2026-08-27
CISA has added six vulnerabilities to its Known Exploited Vulnerabilities catalogue. Five were published between 2015 and 2022, and three grant nothi…
Almost a third of this week's listed vulnerabilities have no severity score Same product 2026-08-25
The weekly vulnerability summary from CISA lists 3882 vulnerabilities for the week beginning 10 August. 1184 of them have no calculated severity scor…
An eighteen-year-old Linux kernel flaw hands ordinary users root Same product 2026-08-08
Tencent Zhuque Lab has found a flaw in the SCTP part of the Linux kernel that has been there since 2008. An ordinary user can use it to gain root, an…

Does this affect you?

A vulnerability matters only if you run the product, in an affected version, somewhere an attacker can reach.

Check your asset list Browse all vulnerabilities

Sources and freshness

CVE

What it is: A reference number naming one specific vulnerability, for example CVE-2024-9474.
What it tells you: Which vulnerability we are talking about, and in which product.
What it does NOT tell you: Nothing about how serious it is, whether anyone is exploiting it, or whether it concerns you.
Why it matters: Without a shared number, vendor, authority and tooling cannot discuss the same flaw.
Used with the others: The number is the key. NVD, KEV and EPSS all describe the same CVE.

NVD CWE CISA KEV EPSS

How to read this together

No single value should be used on its own. A high CVSS score does not mean a vulnerability is being exploited, and a low one does not mean it is harmless. The four sources answer four different questions.

CVE names the specific vulnerability.
NVD adds severity and technical detail about it.
CWE describes the type of mistake behind it.
CISA KEV shows that it is already being exploited.
EPSS estimates how likely exploitation is soon.

The order that decides what is urgent

Do you actually have the product?
Is the version you run affected?
Is it listed in CISA KEV?
Does it have a high EPSS score?
Is the system reachable from the internet or from others?
How important is the system to the business?
Are there compensating controls already in place?

The first two questions are not about the vulnerability at all. They are about you, and they remove most of the list before you start.

A short example

Fix this week

CVSS 6,5 (medium)

In CISA KEV: yes
EPSS: 94 per cent
A firewall facing the internet

Can be scheduled

CVSS 9,8 (critical)

In CISA KEV: no
EPSS: 0,04 per cent
A test server with no internet access

Sorted by CVSS alone, the one on the right comes first. It is the more serious flaw in theory. But the one on the left is being used against real organisations right now, and it sits where an attacker can reach it. That is the one to fix first.

The critical one still has to be fixed. It just does not have to be fixed today.

This product uses the NVD API but is not endorsed or certified by the NVD. CVE and the CVE logo are registered trademarks of The MITRE Corporation; CVE records are used under the CVE Terms of Use. CWE is a trademark of The MITRE Corporation, used per the CWE Terms of Use. KEV data from CISA (CC0). Exploitation probability from EPSS, a FIRST.org project. Open-source package data from OSV and the GitHub Advisory Database (CC-BY 4.0).

Scores and vectors are shown as published by the sources. The ordering of results is Berigo's own editorial assessment, described on the search page, and is not NVD data. An empty result never means a system is safe.