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MISP CVE-2026-94383

| EUVDEUVD-2026-83908 HIGH
Unrestricted Upload of File with Dangerous Type (CWE-434)
2026-09-21 CIRCL GHSA-8q25-97q9-g9wh
8.6
CVSS 4.0 · Vendor: CIRCL
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Attack ChainAIDerived

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

  1. Access
    Authenticate as MISP site-admin
  2. Delivery
    Trigger blocklist workflow with crafted filename
  3. Exploit
    Bypass basename-only sanitization
  4. Execution
    Write script into export directory
  5. Persist
    Request file via web server
  6. Impact
    Execute code as web-server user

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK

2 techniques across 2 tactics: Command and Control, Persistence

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires MISP site-administrator privileges (PR:H) because the blocklist workflow module is role-restricted; the attacker triggers the workflow action with a crafted blocklist filename whose extension is not validated (only basename() and empty/dot checks applied). Actual code execution additionally requires that the underlying web server is configured to interpret and execute scripts from the MISP export directory - a non-default deployment/hardening condition that is the true gate on impact. No user interaction beyond triggering the action; affected versions are MISP <2.5.47.

Impact

This is a genuine RCE (CWE-434) but heavily gated by privilege: the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N) requires site-administrator role, which the description confirms is enforced on the blocklist workflow module. The 8.6 score is driven by full CIA compromise of the web-server process, not by ease of reach - an attacker already holding MISP site-admin is a high trust bar, making this primarily a post-compromise privilege-to-OS escalation / insider-abuse issue rather than a broadly exploitable perimeter flaw. No EPSS, KEV, SSVC, or public POC data is provided, so exploitation is 'no public exploit identified at time of analysis.' A key limiting condition beyond privilege: exploitation only yields code execution IF the web server is configured to interpret/execute scripts from the MISP export directory - a non-default hardening-dependent precondition. The patch (extension allowlist) is confirmed available via the vendor commit. Net: real and worth patching promptly, but not an emergency for internet-facing mass exploitation given PR:H plus the server-config dependency.

Exploit ScenarioDerived

A malicious or compromised MISP site-administrator triggers the blocklist workflow action with a crafted filename parameter carrying an arbitrary extension (e.g. a .php name), which basename()/empty-checks fail to reject, dropping an attacker-controlled script into the MISP export directory. If the web server executes scripts from that directory, the attacker requests the file to run arbitrary code as the web-server user. No public POC is identified; exploitation requires the pre-existing site-admin role and a script-executing export directory.

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 21, 2026

Arbitrary code execution in MISP (Malware Information Sharing Platform) before version 2.5.47 arises because the blocklist workflow module writes a user-supplied filename into the MISP export directory after applying only basename() path stripping and empty/dot checks, leaving the file extension unvalidated. An attacker holding the MISP site-administrator role - the only role permitted to invoke this workflow module (PR:H per the assessed vector) - can therefore place a file with an executable extension in that directory, and if the underlying web server is configured to interpret scripts there, the file executes with the web server user's privileges, compromising confidentiality, integrity and availability. This is a genuine CWE-434 unrestricted file upload, but exploitation is gated both by the high privilege requirement and by the non-default web server configuration that executes scripts from the export path; no public exploit identified at time of analysis, and the flaw is addressed by the vendor's extension allowlist fix in 2.5.47.

RemediationAI

Upgrade MISP to 2.5.47 or later, which contains the extension allowlist fix from commit e5a943178 (https://github.com/MISP/MISP/commit/e5a943178) restricting blocklist filenames to txt, list, blocklist and csv extensions; vendor-released patch: 2.5.47. If immediate upgrade is not possible, the most effective compensating control is to remove script execution from the MISP export directory - for Apache, drop the PHP/CGI handler for that path via a <Directory> block with php_admin_flag engine off or an explicit RemoveHandler .php directive, and for nginx remove the fastcgi_pass/location ~ \.php block that covers the export path so files there are served only as static content; this fully closes the RCE path but changes behaviour only for that directory, with the side effect that any legitimate dynamic content under export/ will stop working. A complementary, lower-effort mitigation is to disable or deactivate the blocklist workflow module entirely until patched, accepting the loss of blocklist export automation, and to treat the MISP site-administrator role as a highly trusted account by auditing existing admins, enforcing strong authentication/2FA on that role and removing dormant administrator accounts, since the vulnerability is only reachable by that role (PR:H). Because the bug is a file-write primitive, also review the MISP export directory for unexpected or recently modified files with script extensions as a post-exploitation indicator, and note that no public exploit code was identified at time of analysis, so this is precautionary rather than reactive hardening.

Affected VersionsENISA

MISP 0 <2.5.47

Affected Packages

euvd misp fix: 2.5.47

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 is a PHP/CakePHP threat-intelligence sharing platform whose workflow engine is implemented as modules under app/Model/WorkflowModules/, with the blocklist action handled by Module_blocklist_action.php. The vulnerable code accepted a caller-supplied blocklist filename parameter and sanitised it with only basename() (to strip path traversal components) plus a rejection of empty or '.' values; it never constrained the file extension, so any extension could be written into the export directory - the classic CWE-434 unrestricted upload of a file with a dangerous type, which is only converted into code execution when the file lands in a web-accessible path that the server is configured to execute. The upstream fix at commit e5a943178 introduces a whitelist check using pathinfo($blocklistFilename, PATHINFO_EXTENSION) and rejects anything outside ['txt', 'list', 'blocklist', 'csv'], failing the workflow with the error 'Blocklist filename has an invalid extension.' Affected code is identified by CPE cpe:2.3:a:misp:misp:*:*:*:*:*:*:*:*. The assessed CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H reflects that the attack is network-reachable but requires the site-administrator privilege (PR:H) and a deployment condition - a web server that executes scripts in the export directory - that is not present in a default, hardened installation; the vendor's CVSS 4.0 vector (8.6) rates AC:L/AT:N, i.e. it does not elevate severity beyond high because of the privileged pre-requisite, which is a static role rather than a remote unauthenticated entry point.

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Severity by source

Vendor (CIRCL) PRIMARY 8.6 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
vuln.today AI 6.6 MEDIUM

Site-admin required (PR:H); AC:H because RCE depends on the non-default condition that the web server executes scripts from the export directory; full CIA impact on the web-server process, scope unchanged.

3.1 AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/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
High
User Interaction
None
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
High
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

The MISP blocklist workflow module accepted a user-supplied blocklist filename parameter without validating the file extension. The only sanitization applied was basename() to strip path components and a check for empty or dot values. A site administrator could specify a filename with an arbitrary extension that would be placed in the MISP export directory. If the underlying web server is configured to interpret and execute scripts from that directory, the resulting file could be invoked, leading to arbitrary code execution in the context of the web server process.

The vulnerability requires the attacker to hold site-administrator privileges within MISP, as the blocklist workflow module is restricted to that role. No additional user interaction is required beyond triggering the workflow action with a crafted filename parameter. The impact is full compromise of the MISP server's confidentiality, integrity, and availability, as arbitrary script execution grants the attacker the same privileges as the web server user.

Version affected: <2.5.47

Executive ViewAI

Why It Matters

CVE-2026-94383 in MISP before 2.5.47 is a high-severity code-execution flaw that could let a site administrator run malicious files on the server if the web server is configured to execute scripts from the export directory. This could expose or disrupt sensitive threat intelligence, sharing configurations, and related security operations. The risk is limited by the high privilege requirement and a non-default web server setting, but affected organizations should treat patching as a priority.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 74% exploitable
Prevalence
Medium
widely used open-source threat-intel sharing platform, but security-team niche
Social Media
1
Sightings
Data Quality
5 sources
Confidence: Medium

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
No
Human Impact
High
Technical Impact
Total

Priority Score

43
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +43
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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