What is the CVSS score of CVE-2026-103239?

CVE-2026-103239 has a CVSS 4.0 base score of 8.6 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N. EPSS exploitation probability: 0.4%.

How to fix or mitigate CVE-2026-103239?

Within 24 hours, inventory all MISP instances and confirm whether any are running versions before 2.5.48; apply Vendor-released patch: MISP 2.5.48 or later to internet-accessible and high-value instances first, and if immediate patching is not possible, restrict network access to trusted users and temporarily remove perm_tag_editor from non-administrative accounts. Within 7 days, complete patching across all remaining MISP instances to 2.5.48 or later, review audit logs for tag collection create/edit activity by non-administrative tag editors, and inspect for unauthorized User or Organisation records or new site-administrator accounts; disable or revert any suspicious accounts, rotate credentials for affected administrators, and validate account and organization data integrity. Within 30 days, formalize least-privilege review of perm_tag_editor delegation, limit MISP administrative access to required personnel, add monitoring and alerting for tag collection changes and account creation, and document an emergency patch cadence for MISP and other threat-intelligence platforms.

MISP CVE-2026-103239

Q: Which versions of MISP are affected by CVE-2026-103239?

MISP deployments prior to 2.5.48 are exposed to a high-severity privilege-escalation flaw that lets users with delegated tag-editor permissions create or modify accounts and reach site-administrator…. A patch is available.

EUVD-2026-89761 HIGH

Improper Access Control (CWE-284)

2026-09-30 CIRCL

GHSA-vpmp-h7jx-6gfx

PHP Authentication Bypass Privilege Escalation Misp

8.6

CVSS 4.0 · Vendor: CIRCL

View

Attack ChainAIDerived

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

Access

Authenticate as tag-editor user
Delivery

Craft TagCollection add/edit request with injected User/Organisation fields
Exploit

saveAssociated writes sibling records
Execution

Create or elevate account to site admin
Impact

Full administrative control of MISP

Vulnerability Assessment

Weakness	CWE CWE-284 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V8 - Authorization Access control enforcement MITRE ATT&CK 1 technique across 1 tactic: Defense Evasion 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 an authenticated MISP account holding the tag editor permission (perm_tag_editor) and network access to the instance; no user interaction or admin rights are needed. Exploitation targets the tag collection add and editWithTags actions, which in vulnerable versions (< 2.5.48) call CakePHP's saveAssociated() on the full HTTP request payload, allowing associated User/Organisation model data to be injected and persisted. The limiting factor is the tag-editor privilege prerequisite (PR:L) - the instance must have granted this role to a semi-trusted user; default single-admin deployments with no delegated tag editors are not exploitable by external actors.
Impact	This is a genuine high-priority issue rather than an inflated CVSS score. The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H) is well-supported by both the description and the source-code diff: the flaw is remotely reachable over the network, requires only low privileges (any account with perm_tag_editor), needs no user interaction, and yields full confidentiality and integrity impact through creation/modification of privileged User and Organisation records culminating in site-administrator takeover. No EPSS score, KEV listing, or SSVC decision data was provided, and no public POC is referenced, so exploitation likelihood signals are absent - but the root cause is a classic CakePHP mass-assignment (saveAssociated over the raw request payload) that is trivially understood and exploitable by anyone who can read the patch commit (96f735e7b). The single caveat is that exploitation is gated behind an existing authenticated, tag-editor-level account, which meaningfully narrows the attacker population versus a pre-auth flaw. Net: real priority for any MISP operator, driven by high impact and low complexity, tempered only by the PR:L prerequisite and MISP's specialized deployment footprint.
Exploit ScenarioDerived	An analyst or partner granted the tag-editor role on a shared MISP instance sends a crafted add/editWithTags request that appends User or Organisation model fields (e.g. a new admin user, or an org_id/role change) alongside the legitimate TagCollection data. Because the controller passed the entire payload to saveAssociated(), the injected sibling records are written to the database, letting the attacker mint or elevate an account to site administrator. No public exploit is identified at time of analysis, but the fix commit clearly reveals the vulnerable code path.

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

Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 30, 2026

Privilege escalation in MISP before 2.5.48 allows an authenticated user who holds the tag editor permission (perm_tag_editor) to smuggle sibling User and Organisation records into tag collection create or edit requests, which the affected controller then persists alongside the intended tag collection - letting the attacker create or modify accounts and escalate to site administrator. Exploitation requires network access to the instance and a delegated tag-editor role; no user interaction or administrative rights are needed, and the accompanying source fix (commit 96f735e7b) shipped in MISP 2.5.48. No public exploit code was identified at time of analysis, and instances that never delegate perm_tag_editor to non-administrative accounts are not exposed to an unprivileged external actor.

RemediationAI

Upgrade to MISP 2.5.48 or later; the vendor patch is the source commit 96f735e7b (https://github.com/MISP/MISP/commit/96f735e7b), which stops passing the raw request payload to saveAssociated() and rebuilds tag collection saves as an explicit TagCollection save plus individual TagCollectionTag rows. If an immediate upgrade is not possible, remove the perm_tag_editor permission from every non-administrative role and user account until patched - the trade-off is that legitimate tag-curation workflows for those users stop working, so review whether the role is actually needed. In parallel, treat the instance as potentially compromised: audit the users and organisations tables for accounts created or modified outside normal admin flows, paying particular attention to newly created or recently altered accounts carrying site-admin or org-admin flags, and rotate credentials for any privileged account that may have been created or touched. Because the injection happens in the request body of tag collection add/edit calls, log inspection or WAF rules that flag unexpected sibling model keys (User, Organisation, or other non-TagCollection roots) in POST/PUT bodies to /tagCollections/addWithTags and /tagCollections/editWithTags provide useful detection during the exposure window; note this is detective-only and does not prevent exploitation on its own, and that restricting network access to the MISP interface to trusted networks limits but does not eliminate risk from a legitimate-but-malicious tag editor account.

Affected VersionsENISA

MISP 0 <2.5.48

Affected Packages

euvd misp fix: 2.5.48

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

MISP (Malware Information Sharing Platform) is a PHP/CakePHP threat-intelligence sharing application, tracked as cpe:2.3:a:misp:misp:*:*:*:*:*:*:*:*. The flaw is rooted in CWE-284 (Improper Access Control) as exercised through the CakePHP ORM: the TagCollectionsController's addWithTags and editWithTags actions passed the entire HTTP request payload ($this->request->data) straight into the model's saveAssociated() call. saveAssociated() recursively saves associated models, so any extra top-level model keys present in the JSON or form body - a User record, an Organisation record - were treated as legitimate associations of the tag collection and written to the database, even though the caller only ever had permission to curate tags. Because the primary TagCollection row had its org_id/user_id pinned to the current user, the injected sibling records were the interesting payload; the diff shows the fix replaces saveAssociated() with an explicit save() of only ['TagCollection' => ...] plus per-row TagCollectionTag inserts, so a plain save() cannot write belongsTo siblings no matter what associations the models gain later. The same commit also strips a caller-supplied TagCollection[id] from the create path, closing a related id-smuggling issue where an id in the payload turned the insert into a covert UPDATE of an arbitrary tag collection that was then re-owned to the attacker.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (CIRCL) PRIMARY 8.6 HIGH

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

vuln.today AI 8.1 HIGH

Network-reachable with low complexity; PR:L for the required tag-editor role; full confidentiality/integrity via admin account creation, no availability impact, scope unchanged within the application.

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

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

Primary rating from Vendor (CIRCL).

CVSS VectorVendor: CIRCL

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

Low

User Interaction

None

Vulnerable system: Confidentiality

High

Vulnerable system: Integrity

High

Vulnerable system: Availability

None

Subsequent system: Confidentiality

None

Subsequent system: Integrity

None

Subsequent system: Availability

None

DescriptionCVE.org

MISP contains a privilege escalation vulnerability in the tag collection creation and editing functionality. The affected actions accepted the full HTTP request payload and passed it to a bulk-association save operation, which writes not only the intended tag collection record but also any associated model data present in the payload.

A user holding the tag editor permission could craft a request that includes additional model data (such as User or Organisation records) alongside the tag collection fields. Because the save operation processed all associated models indiscriminately, the injected sibling records were written to the database, enabling the attacker to modify or create privileged accounts and escalate to site administrator.

Preconditions:

An authenticated account with the tag editor permission (perm_tag_editor)
Network access to the MISP instance

Impact:

Unauthorized creation or modification of User and Organisation records
Privilege escalation from tag editor to site administrator

Affected versions: < 2.5.48

Executive ViewAI

Why It Matters

MISP deployments prior to 2.5.48 are exposed to a high-severity privilege-escalation flaw that lets users with delegated tag-editor permissions create or modify accounts and reach site-administrator control. No public exploit identified at time of analysis, but successful abuse would give an unauthorized party administrative access to the MISP instance and its user and organization records. Leadership should prioritize patching to 2.5.48 and auditing any non-administrative accounts holding tag-editor rights.

Business Impact: High

Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score

0.4%

Top 74% exploitable

Prevalence

Medium

Widely used open-source threat-intel sharing platform among CERTs/SOCs, not general-population software

Data Quality

4 sources

Confidence: Medium

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 0.4%

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

Total

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +43

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Authentication Bypass CRITICAL

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

Privilege Escalation HIGH

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.