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Zammad EUVDEUVD-2026-87269

| CVE-2026-63204 LOW
Authorization Bypass Through User-Controlled Key (CWE-639)
2026-09-25 GitHub_M
2.3
CVSS 4.0 · Vendor: GitHub_M
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Attack ChainAIDerived

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

  1. Access
    Authenticate as agent
  2. Exploit
    Enumerate ai_analytics_run_error_id values
  3. Execution
    Call summarize endpoint with foreign run ID
  4. Impact
    Receive provider error string for inaccessible ticket

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Object-level authorization, IDOR prevention
Exploitation Conditions

Requires an authenticated account with agent permissions on the target Zammad instance (PR:L) and access to the ticket summarize endpoint. The attacker must supply a valid ai_analytics_run_error_id (AT:P) that references a run which recorded a provider error - meaning the AI analytics/summarize feature must be in use and an errored run must exist. Disclosure is strictly limited to the provider error string; ticket content is never exposed. Affects all Zammad versions prior to 7.1.2. No user interaction and no non-default configuration beyond the AI summarize feature being present.

Impact

All signals point to a genuinely low-priority issue. The vendor-supplied CVSS 4.0 vector (AV:N/AC:L/AT:P/PR:L/UI:N/VC:L, base 2.3) is consistent with the description: an authenticated agent-level user leaks only a stored AI provider error string, with no integrity or availability impact and confidentiality rated Low. The AT:P (attack requirement present) reflects that the attacker must know or guess a valid ai_analytics_run identifier for a run that actually recorded an error. No EPSS score, no CISA KEV listing, and no public POC are present in the input - no public exploit identified at time of analysis. The single 'reference' beyond the disclosure is the fix commit itself (adds authorize!(ai_analytics_run_error, :show?)), which confirms the root cause but does not weaponize it. There is no conflict between the description and the CVSS vector; both agree this is an authenticated, low-impact information disclosure. The one metadata problem is the 'Authentication Bypass' tag, which is inaccurate - this is a per-record authorization (IDOR) flaw, not an authentication bypass. Bottom line: real but minor, appropriately scored low, not an urgent patch priority beyond routine Zammad updates.

Exploit ScenarioDerived

An authenticated Zammad agent calls the ticket summarize endpoint and supplies an ai_analytics_run_error_id belonging to a run linked to a ticket outside their permission scope. The endpoint returns the stored AI provider error_message for that run despite the agent lacking access to the underlying ticket. No public POC exists; the fix commit's spec illustrates the exact request but is a regression test, not weaponized exploit code.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 25, 2026

Authenticated agents on Zammad helpdesk instances can retrieve the AI provider error strings recorded for AI analytics runs belonging to tickets they are not authorized to view, simply by passing an arbitrary ai_analytics_run_error_id to the ticket summarize endpoint. The exposure is confined to the stored provider error message - no ticket content, customer data, or conversation text is disclosed - and the AI summarize/analytics feature must be in use with at least one errored run present for the attack to succeed. The vendor-published CVSS 4.0 score is 2.3 and our independent assessment rates it low severity, with only a limited confidentiality impact; no public exploit code or active exploitation has been identified at time of analysis, and the flaw is fixed in Zammad 7.1.2.

RemediationAI

Upgrade to Zammad 7.1.2, the vendor-released patch version, which introduces the object-level authorization check in app/controllers/ticket/summarize_controller.rb; the change is small and self-contained (a single authorize!(ai_analytics_run_error, :show?) call), so the upgrade risk is low and the fix should be applied as part of routine release tracking rather than emergency change. Confirm the patched behavior after upgrading by verifying that requests supplying an ai_analytics_run_error_id tied to an inaccessible ticket return HTTP 403, as covered by the vendor's added request specs. If immediate upgrade is not possible, the most effective compensating control is to remove or suspend the ai_analytics_run_error_id capability from agent-facing clients at the reverse-proxy or API-gateway layer, or to disable the AI summarize/analytics feature entirely while the instance remains unpatched - the trade-off being that agents lose the ticket-summarization functionality that depends on it. Because the issue requires an authenticated account with agent permissions, temporarily tightening agent account provisioning, disabling dormant or shared agent accounts, and reviewing agent role assignments reduces the attacker pool but does not eliminate the exposure for legitimate agents; this should be treated as a stopgap, not a substitute for the 7.1.2 upgrade. Note that the flaw only leaks provider error strings and never ticket content, and no public exploit code or confirmed active exploitation has been observed, so prioritization can follow the vendor's low CVSS 2.3 rating. Full details are in the vendor advisory at https://github.com/zammad/zammad/security/advisories/GHSA-75j9-hpg4-j9f8.

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

This is a classic instance of CWE-639 (Authorization Bypass Through User-Controlled Key), the object-reference class often called IDOR: the application trusts a client-supplied identifier to select a record and then fails to verify that the requesting principal is entitled to that record. In Zammad's Ruby on Rails backend, the ticket summarize flow is handled by app/controllers/ticket/summarize_controller.rb. The endpoint accepts an ai_analytics_run_error_id parameter and loads the corresponding AI analytics run error object, which stores the error string returned by the configured AI provider. Because the controller did not perform an object-level authorization check against the record, any user holding agent permissions could enumerate or guess run identifiers and read error messages attached to runs of foreign, otherwise inaccessible tickets. The upstream fix (commit 849191c32a76f62fbd7cf4582a2b1e05e25f25ed) adds a single object-scoped authorization call, authorize!(ai_analytics_run_error, :show?), which routes the record through Zammad's policy layer before the error payload is returned. The accompanying request specs confirm the corrected behavior: an agent requesting an error from a run tied to an accessible ticket still receives the provider error message, while a request for a run tied to an inaccessible ticket now returns HTTP 403 Forbidden. The CVSS 4.0 vector supplied by the vendor carries the Attack Requirements metric as present (AT:P), reflecting the precondition that the AI analytics feature must be enabled and a failed run must exist; the vector confirms network attack vector, low privileges required, no user interaction, and confidentiality impact limited to low.

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Severity by source

Vendor (GitHub_M) PRIMARY 2.3 LOW
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 4.3 MEDIUM

Remote and low-complexity but requires agent authentication (PR:L); leaks only a provider error string so C:L with no integrity or availability impact.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/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
Present
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
None
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

1
Patch available
Sep 25, 2026 - 19:04 EUVD

DescriptionCVE.org

Zammad is a web based open source helpdesk/customer support system. Prior to 7.1.2, an authenticated user with agent permissions can supply an arbitrary AI analytics run identifier to the ticket summarize endpoint and receive the AI provider error message stored for that run, even if the run belongs to a ticket the agent is not authorized to access. The disclosure is limited to the provider error string; ticket content is not exposed. This issue is fixed in version 7.1.2.

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

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 LOW
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
LOW severity (CVSS 0.1-3.9)
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· derived
Defer
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Low
Technical Impact
Partial

Priority Score

12
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +12
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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