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Backstage Scaffolder EUVDEUVD-2026-94071

| CVE-2026-106506 MEDIUM
Exposure of Sensitive Information Through Data Queries (CWE-202)
2026-10-06 security-advisories@github.com GHSA-vwp5-f99x-x3rq
5.3
CVSS 3.1 · Vendor: github
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Attack ChainAIDerived

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

  1. Access
    Authenticate as low-privilege Backstage user
  2. Delivery
    Craft task-list request ordering on secret field
  3. Exploit
    Abuse unvalidated order-by as inference side channel
  4. Execution
    Repeat requests to deduce secret bytes
  5. Impact
    Reconstruct confidential scaffolder task data

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V14 - Data Protection Sensitive data in outbound message
Exploitation Conditions

Requires an authenticated Backstage user who already holds permission to create and read the relevant scaffolder tasks (PR:L), so this is not remotely reachable by anonymous attackers. Four additional stacked conditions must all hold, per the advisory: (1) the target task's secrets must still be retained rather than purged, (2) the attacker must have visibility of the target task, (3) the attacker must know the structure of the secret being inferred, and (4) the attack needs many repeated list requests manipulating the order-by parameter on secret-bearing fields. These conditions, which map directly to AC:H, sharply limit practical exploitation and mean impact is inference/partial leakage rather than guaranteed full secret disclosure; only deployments on versions prior to the fix with secret retention enabled are exposed.

Impact

This is a genuinely moderate-priority, low-urgency issue rather than a high-impact emergency, and the 5.3 MEDIUM CVSS reflects that accurately. The vector CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N shows network reach but three substantial brakes: high attack complexity (AC:H), required authentication (PR:L), and no integrity or availability impact (I:N/A:N) - only confidentiality (C:H). The description reinforces the AC:H rating by listing multiple stacked preconditions (retained task secrets, visibility of a target task, knowledge of the secret structure, and many repeated requests), confirming this is a slow inference/side-channel leak via the task-list order-by parameter, not a direct dump of secrets. No EPSS score, no CISA KEV listing, and no public exploit code were provided in the intelligence, so exploitation status is 'no public exploit identified at time of analysis.' There is no conflict between signals here - every source (CVSS, CWE-202 exposure-through-data-queries, and the commit that merely restricts order-by to created_at/status/created_by) points consistently to a constrained, authenticated information-inference weakness. The confidentiality rating of C:H should be read with care: the description says an attacker 'may be able to infer' data 'under specific conditions,' so real-world impact is likely partial inference rather than reliable full secret recovery - treat C:H as an upper bound.

Exploit ScenarioDerived

An authenticated Backstage user who holds permission to create and read scaffolder tasks submits task-list requests manipulating the ordering parameter (e.g. order=asc:secrets) against the scaffolder-backend API. By repeatedly reordering results on an unsupported secret-bearing field and observing how a target task sorts relative to others, the attacker incrementally infers confidential task secret data. No public exploit code was identified, and success requires the secret to still be retained, the target task to be visible, and many iterated requests.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 06, 2026

Improper input validation in the Backstage Scaffolder backend (@backstage/plugin-scaffolder-backend) before version 4.1.0 allows an authenticated user with permission to create and read scaffolder tasks to influence how the task list endpoint orders results, enabling inference of confidential task data such as secrets. Exploitation is not straightforward: the assessed vector is CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N (5.3 Medium), and the advisory requires four stacked preconditions - the target task's secrets must still be retained (not purged), the attacker must be able to see the target task, the attacker must already know the structure of the secret being inferred, and the attack depends on many repeated list requests - so the practical outcome is partial inference rather than guaranteed full secret disclosure. There is no public exploit identified at time of analysis, and no KEV listing; the issue is fixed in @backstage/plugin-scaffolder-backend 4.1.0 (Backstage release v1.54.6).

RemediationAI

Upgrade to @backstage/plugin-scaffolder-backend 4.1.0 or later, which corresponds to Backstage release v1.54.6 (see the advisory at https://github.com/backstage/backstage/security/advisories/GHSA-vwp5-f99x-x3rq and the release tag at https://github.com/backstage/backstage/releases/tag/v1.54.6); the fix commit is e673a869449874a9169e8f89852e75e862011b93, which restricts task list ordering to the supported fields created_at, status, and created_by and returns HTTP 400 for anything else. Vendor-released patch: 4.1.0. If an immediate upgrade is not possible, compensating controls should target the stated preconditions: purge or shorten retention of scaffolder task secrets so the inference side channel has no retained material to leak (side effect: removal of useful task history and troubleshooting data), and tighten scaffolder RBAC so that only trusted identities hold the combination of task creation and task read permissions, since PR:L means an authenticated user with those rights is required (side effect: reduced self-service for template users). Deployments that cannot apply both controls should treat the residual exposure as limited to partial secret inference for users who already have task visibility.

Affected VersionsENISA

backstage < 1.54.6
plugin-scaffolder-backend < 4.1.0

Affected Packages

npm @backstage/plugin-scaffolder-backend fix: 4.1.0
euvd backstage fix: 1.54.6
euvd plugin_scaffolder_backend fix: 4.1.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 3 packages in npm, euvd

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

Technical ContextAI · show details

The flaw is an instance of CWE-202 (Exposure of Sensitive Information Through Data Queries), rooted in the Backstage scaffolder backend's task list endpoint accepting an attacker-controlled ordering parameter. The vulnerable code parsed an order expression such as 'asc:secrets' and passed the chosen field straight into the underlying task query, letting a caller order results by arbitrary fields (including secret-bearing ones) rather than only the intended safe columns. By repeatedly requesting the list with different ordering on a field that embeds secret material, and comparing the resulting order, an attacker with visibility of a target task and prior knowledge of the secret's structure can infer confidential values through the ordering side channel. The upstream fix (commit e673a869449874a9169e8f89852e75e862011b93) introduces an explicit allowlist, taskOrderFields, containing only 'created_at', 'status', and 'created_by'; any order field outside that set now throws an InputError and the request is rejected with HTTP 400 (openapi.yaml and router.ts gained a 400/ErrorResponse path). A regression test asserts that GET /v2/tasks?order=asc:secrets returns 400 and that the task broker's list method is never invoked, confirming the query is short-circuited before reaching the datastore. The affected component is the scaffolder-backend plugin, which powers Backstage's software template task execution and task listing API.

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Severity by source

Vendor (github) PRIMARY 5.3 MEDIUM
AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 5.3 MEDIUM

Network-facing API (AV:N) but requires an authenticated task-reading user (PR:L) and multiple stacked preconditions plus iterated requests (AC:H); only confidential task data is inferred, so I:N/A:N.

3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
4.0 AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Red Hat 5.3 MEDIUM

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

1
Patch available
Oct 06, 2026 - 23:05 EUVD

DescriptionCVE.org

Backstage is an open framework for building developer portals. Prior to 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by improper input validation in scaffolder task list ordering. An authenticated Backstage user with permission to create and read relevant scaffolder tasks may be able to infer confidential task data under specific conditions. Successful exploitation requires retained task secrets, visibility of a target task, knowledge of the secret structure, and repeated requests. This issue is fixed in version 4.1.0.

Threat Intelligence Overview

EPSS Score
0.2%
Top 89% exploitable
Prevalence
Medium
popular open-source CNCF developer portal, common in platform-engineering orgs
Threat Intel
1
1 source
Data Quality
7 sources
Confidence: High
EUVD 🇯🇵JVN NVD CVE.org EPSS Vulnrichment GHSA Vendor GitHub VulDB

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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

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

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Vendor StatusVendor

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