GCVE-1-2026-20227 (CVE-2026-103235)

Vulnerability from gna-1 – Published: 2026-09-30 09:09 – Updated: 2026-09-30 09:12
VLAI
Title
MISP Event Delegation Mass Assignment Allows Retargeting Delegation to Arbitrary Events
Summary
MISP contains a mass assignment vulnerability in the event delegation feature. When a user with delegation permission submits a delegation request, the application authorized the user against the event identified in the URL but then persisted the entire submitted record, including caller-supplied fields such as the primary key and event_id. An authenticated attacker could inject a primary key or event_id into the delegation payload to retarget an existing delegation record to any event on the instance. Because a delegation row grants the requesting organisation read access to the event it references, this effectively granted read access to arbitrary events belonging to other organisations. If the target organisation subsequently accepted the delegation, ownership of the event was transferred and the original record was deleted. Preconditions: - An authenticated user with the delegation permission (perm_delegate) - The MISP.delegation server setting must be enabled Impact: - Confidentiality: read access to any event on the instance - Integrity: overwriting existing delegation records and transferring event ownership Affected versions: MISP < 2.5.48
Severity
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
CWE
  • CWE-915 - Improperly Controlled Modification of Dynamically-Determined Object Attributes
  • CWE-639 - Authorization Bypass Through User-Controlled Key
Assigner
GNA-1 This instance Scorecard
References
Impacted products
Vendor Product Version CPE status
MISP MISP Affected: 0 , < 2.5.48 (semver)
    cpe:2.3:a:misp:misp:*:*:*:*:*:*:*:*
Create a notification for this product.
Credits
Jeroen Pinoy iglocska Claude Opus 5
GCVE extensions
AI involvement GCVE-BCP-05-X-01
Whole record AI-generated Human-reviewed GNA-1

Draft vulnerability metadata was generated from a git-format patch using an Ollama-hosted language model. Human validation is required before publication.

ai-computer-assisted:llm-generatedai-computer-assisted:classification
Model Source Identifier
qwen3.8:27b ollama qwen3.8:27b
Patch provenance GCVE-BCP-05-X-02
Generator
patch2vuln.py on 2026-09-30 07:37
Model
qwen3.8:27b
Input
https://github.com/MISP/MISP/commit/d1f5684f9.patch f478751165e6…
Confidence
high
Commit Subject Patch SHA-256
d1f5684f9a19 fix: [security] Delegation requests stay bound to the event f478751165e6…
Fix summary

The delegation record is now constructed from a strict allow-list of fields rather than persisting the raw user-submitted payload. The event_id is always derived from the authorized event in the URL, the requester_org_id is always taken from the authenticated session, and the primary key is never included in the saved data. Only message, distribution, and sharing_group_id are accepted from user input, eliminating the ability to retarget or overwrite existing delegation records.

Patch summary

In EventDelegationsController::delegateEvent(), the code previously saved $this->request->data['EventDelegation'] directly after setting a few fields. The fix replaces this with an explicit allow-list array containing only event_id (from the authorized URL event), requester_org_id (from the session), org_id (resolved from submitted UUID), message, distribution, and sharing_group_id. The primary key id is never included. A regression test class DelegationRequestRetargeting was added to verify that injecting a nested EventDelegation with a foreign id and event_id does not grant read access to the victim event.

CVSS rationale

Network vector: MISP is a web application accessible over HTTP. Low complexity: a single crafted POST request suffices. No attack target manipulation. Low privileges: requires an authenticated user with perm_delegate. No user interaction: read access is granted immediately upon creating the retargeted delegation. High confidentiality: grants read access to any event on the instance. High integrity: overwrites existing delegation records and can transfer event ownership. No availability impact without victim acceptance. Scope change (SC:H, SI:H): the vulnerability crosses organisational boundaries, affecting data owned by other organisations. No sub-system availability impact.

Weakness rationale
  • CWE-915 The application persisted the entire user-submitted record including fields (id, event_id) that should not be attacker-controllable, allowing mass assignment of sensitive fields to retarget the delegation.
  • CWE-639 The authorization check validated only the event in the URL, but the attacker-supplied primary key or event_id in the payload redirected the operation to a different record, bypassing the intended authorization boundary.
Attack pattern rationale
  • CAPEC-12 The attacker manipulates hidden or additional fields in a form/API request (injecting id and event_id into the EventDelegation payload) to modify data beyond what the application intended to accept. This is the canonical mass assignment pattern: the server processes user-supplied fields it should have ignored. The mapping is direct and well-supported by the patch evidence.
Assumptions to verify
  • The affected version boundary (< 2.5.48) is inferred from the tag_version_boundary metadata showing v2.5.48 as the nearest tag with 22 commits after the fix; the exact last affected release is not explicitly stated in the patch.
  • PR:L assumes the attacker needs only the perm_delegate permission, which is a non-admin role; the exact role configuration may vary by deployment.
  • VA:N assumes the availability impact (deletion of the original event) requires victim acceptance and is therefore not a direct availability impact of the vulnerability itself.
  • The CAPEC-12 mapping is the closest standard pattern; the vulnerability also has IDOR characteristics (CWE-639) but CAPEC-12 best captures the mass-assignment mechanism demonstrated in the patch.
  • The MISP.delegation server setting must be enabled for the vulnerability to be exploitable; this is a deployment configuration assumption.
Model comparison

Selected qwen3.8:27b by deterministic-consensus-v1
The selected result is closest to model consensus; this heuristic does not establish factual correctness and human review remains required.

Model Score Agreement Confidence Assumptions
qwen3.8:27b 6 9 high 5
To clipboard 

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