What is the CVSS score of EUVD-2026-87263?

EUVD-2026-87263 has a CVSS 4.0 base score of 7.1 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. EPSS exploitation probability: 0.3%.

How to fix or mitigate EUVD-2026-87263?

Within 24 hours, confirm whether your organization runs Zammad and, if so, identify all instances on versions prior to 7.1.2, restricting or disabling the External Data Source feature on internet-exposed or multi-tenant deployments as a stopgap and reviewing logs for enumerable-ID lookups against ticket_id, customer_id, user_id, group_id, and organization_id parameters. Within 7 days, upgrade all affected instances to the vendor-released patch, Zammad 7.1.2, which adds the missing explicit authorization check, and validate the upgrade in a staging environment first, then audit customer-facing account provisioning so that low-privilege accounts are issued only where there is a genuine business need. Within 30 days, verify the production upgrade across every instance, retrospectively review access logs for anomalous bulk or sequential record access that could indicate prior exploitation (noting that no public exploit code or confirmed active exploitation was identified at time of analysis), and put in place routine version tracking so Zammad deployments are patched promptly going forward.

Zammad EUVD-2026-87263

Q: Which versions of Zammad are affected by EUVD-2026-87263?

A broken access control flaw in Zammad's External Data Source feature allows any logged-in user - including the lowest-privilege customer account - to retrieve help desk records belonging to other…. A patch is available.

| CVE-2026-84464 HIGH

Information Exposure (CWE-200)

2026-09-25 GitHub_M

Information Disclosure Ruby Zammad

7.1

CVSS 4.0 · Vendor: GitHub_M

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Authenticate as basic customer
Delivery

Call external_data_source API
Exploit

Reference another record's ID
Execution

Server skips authorization check
Impact

Foreign ticket/user/org details disclosed

Vulnerability Assessment

Weakness	CWE CWE-200 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V14 - Data Protection Data exposure prevention MITRE ATT&CK 2 techniques across 2 tactics: Collection, Discovery The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	Requires (1) a Zammad instance older than 7.1.2 with the External Data Source feature configured/used to look up records from an external system, and (2) any authenticated account - including a minimal customer-level account with no special privileges. The attacker must know or guess a target record's numeric ID (ticket, user/customer, group, or organization), which is enumerable. Exploitation is limited to confidentiality (reading others' records); it grants no write or availability impact, requires no user interaction from a victim, and does nothing on instances that do not use the External Data Source feature.
Impact	This is a genuine but moderate-severity broken-access-control (IDOR) flaw, not a high-CVSS-but-empty issue, yet several signals keep real-world urgency low. The vendor-assigned CVSS 4.0 vector (AV:N/AC:L/PR:L/UI:N/VC:H, no integrity or availability impact) matches the description exactly - a purely confidentiality-affecting authorization bypass reachable over the network by any authenticated user. PR:L is well-supported: the description explicitly states even a basic customer account suffices, so the barrier is low but non-zero. No EPSS score, KEV listing, or public POC is present in the input, so there is no evidence of active or automated exploitation - this signal is consistent (all three exploitation indicators are absent), meaning the 7.1 rating reflects impact-and-ease, not observed attacks. The commit diff and added RSpec tests confirm the root cause and fix, raising confidence in the technical claim. Net: real and worth patching for Zammad operators, but its niche footprint, requirement for a valid account, and dependence on the External Data Source feature being configured make it a routine-patch priority rather than an emergency.
Exploit ScenarioDerived	An attacker registers or already holds a basic customer account on a Zammad instance whose External Data Source feature is enabled. They send an authenticated API request to /api/v1/external_data_source/... supplying another record's ID in search_context (e.g. ticket_id, customer_id, group_id, or organization_id), and the server includes that unauthorized record's details in the render context / outbound external lookup, disclosing foreign tickets, customer accounts, teams, or organizations. No public exploit code is identified at time of analysis, though the fix commit and test cases make the vector straightforward to reproduce.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 25, 2026

An authenticated broken-access-control flaw in Zammad's External Data Source feature lets any logged-in user - including a minimal customer-level account - read records that do not belong to them by supplying another record's numeric ID. The affected component builds a 'render context' from request parameters such as ticket_id, customer_id, user_id, group_id, and organization_id and passes it to the configured external system lookup without first checking whether the requesting user is permitted to see that record, so enumerable IDs leak ticket, user, group, and organization details. The issue affects Zammad versions prior to 7.1.2, where the vendor-released patch (7.1.2) adds an explicit authorization check; no public exploit code or confirmed active exploitation was identified at time of analysis.

RemediationAI

Upgrade to Zammad 7.1.2, which is the vendor-released patch and introduces the authorized_record/authorized?(record, :show?) check on every record pulled into the External Data Source render context; consult the vendor advisory at https://github.com/zammad/zammad/security/advisories/GHSA-jvm2-cr58-4qxp and the fix commit at https://github.com/zammad/zammad/commit/34bdf46273adbea03821ac7157c8beaacde03a4b for verification. If an immediate upgrade is not possible, the most effective compensating control is to disable or remove the External Data Source object lookups that administrators have configured (or block the /api/v1/external_data_source/* endpoints at the reverse proxy); the trade-off is that any form field relying on external lookups stops auto-completing or resolving values, which breaks dependent workflows. Restricting access to those endpoints to trusted internal networks or specific roles limits exposure but does not fix the underlying authorization gap, since the vulnerable code path is still reachable by any authenticated user with network access, and ID values remain enumerable. Because exploitation requires only a valid low-privilege login, audit logs for /api/v1/external_data_source requests containing search_context parameters during the exposure window to identify any records that may have been read, and rotate or restrict anything sensitive that was exposed through a third-party lookup.

Affected VersionsENISA

Zammad < 7.1.2

Affected Packages

euvd zammad fix: 7.1.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Zammad is a Ruby on Rails helpdesk/customer-support platform, and the flaw sits in the External Data Source feature, which lets administrators query records from a third-party system and merge the returned values into Zammad forms. The controller at app/controllers/external_data_source_controller.rb assembled a render context by looking records up directly with model.find_by(id: param_value) for each model referenced in the query string (ticket, user/customer, group, organization), then handed that context to the ExternalDataSource object that issued the outbound lookup. Because no policy check ran between the lookup and the outbound request, the controller effectively acted as an authorization-blind proxy: any object the user could name by ID was resolved and its attributes forwarded. This is CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) realized as an insecure direct object reference / missing function-level access control. The fix replaces the raw lookups with an authorized_record(model, id) helper that returns nil unless authorized?(record, :show?) passes, so unauthorized records are simply omitted from the render context, and the accompanying spec changes confirm the intended behavior for agents without group access, unrelated customers, unrelated organizations, and unrelated users (the last case falling back to the current user). The assessed CVSS:3.1 vector AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N matches the code evidence: pure confidentiality impact, authenticated (PR:L), no user interaction, no scope change, and no integrity or availability effect.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (GitHub_M) PRIMARY 7.1 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

vuln.today AI 6.5 MEDIUM

Network-reachable API needing only a low-privilege authenticated (basic customer) account, no user interaction, high confidentiality disclosure of foreign records but no integrity or availability impact.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

Low

User Interaction

None

Vulnerable system: Confidentiality

High

Vulnerable system: Integrity

None

Vulnerable system: Availability

None

Subsequent system: Confidentiality

None

Subsequent system: Integrity

None

Subsequent system: Availability

None

Lifecycle Timeline

Patch available

Sep 25, 2026 - 19:04 EUVD

CVE Published

Sep 25, 2026 - 18:18 cve.org

HIGH 7.1

DescriptionCVE.org

Zammad is a web based open source helpdesk/customer support system. Prior to 7.1.2, zammad's External Data Source feature, used to look up records from an external system, did not properly verify whether a user was allowed to see a specific ticket, user, group, or organization before including its details in a request to that external system. An authenticated user, including one with only basic customer access, could exploit this by referencing another record's ID, and thereby view details of tickets, customer accounts, teams, or organizations that did not belong to them. This issue is fixed in version 7.1.2.

Technical POC Analysis

Evidence basis: GHSA-jvm2-cr58-4qxp (published 2026-08-04, reporter r00k1e-sec).

Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.

Executive ViewAI

Why It Matters

A broken access control flaw in Zammad's External Data Source feature allows any logged-in user - including the lowest-privilege customer account - to retrieve help desk records belonging to other users and organizations simply by changing a numeric identifier in a request. Because the exposed data spans tickets, users, groups, and organizations, the flaw can leak the full breadth of an organization's support history, customer identities, and internal structure to anyone who can obtain a basic account, and it affects all deployments running Zammad versions prior to 7.1.2. Leadership should treat this as a customer-data confidentiality and contractual/regulatory exposure issue rather than a purely technical defect, since impact scales with the size of the customer base and the sensitivity of ticket content.

Business Impact: High

Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score

0.3%

Top 81% exploitable

Prevalence

Low

niche self-hosted open-source helpdesk, limited enterprise footprint

Data Quality

6 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

Vulnrichment

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.3%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision

Scheduled

Exploitation

None

System Exposure· derived

Open

Automatable

Human Impact

High

Technical Impact

Partial

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +36

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.