Cross-Site Request Forgery via Attacker-Controlled REST Detection in MISP
Summary
| CVE | CVE-2026-85547 |
|---|---|
| State | PUBLISHED |
| Assigner | CIRCL |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-04 10:17:14 UTC |
| Updated | 2026-09-04 17:17:03 UTC |
| Description | A cross-site request forgery (CSRF) vulnerability exists in MISP due to form-security and CSRF protections being disabled based on whether an incoming request was identified as a REST request. MISP's REST detection can be influenced by request properties such as the URL suffix or the HTTP Accept header. Because Accept: application/json can be supplied by a cross-origin page without requiring a CORS preflight, an attacker could cause a request originating from another website to be treated as REST traffic. MISP would consequently disable its normal form-security and CSRF validation even though the request was authenticated using the victim's existing browser session. An unauthenticated remote attacker could exploit this behavior by convincing an authenticated MISP user to visit or interact with a malicious web page. The attacker's page could then issue crafted requests to susceptible state-changing MISP endpoints using the victim's privileges. Depending on the permissions of the victim and the targeted endpoint, this could allow unauthorized modification, creation, publication, or removal of data and other state changes. The vulnerability originates from granting the form-security exemption based on _isRest() rather than on the authentication mechanism used by the request. The patch changes this behavior so that CSRF and form-security exemptions are granted only when the request actually carries a MISP API key. Session-authenticated REST-style requests remain subject to CSRF protection. The fix also introduces support for transmitting CSRF tokens through the X-CSRF-Token header for legitimate same-origin AJAX requests. Such a header cannot normally be attached by a cross-origin page without triggering a CORS preflight, preventing it from being used to reproduce the original attack. |
Risk And Classification
Primary CVSS: v4.0 6.2 MEDIUM from 5a6e4751-2f3f-4070-9419-94fb35b644e8
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:L/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.003430000 probability, percentile 0.272130000 (date 2026-09-07)
Problem Types: CWE-352 | CWE-352 CWE-352 Cross-Site Request Forgery (CSRF)
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 5a6e4751-2f3f-4070-9419-94fb35b644e8 | Secondary | 6.2 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:L/SA:H/E:X/C... |
| 4.0 | CNA | CVSS | 6.2 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:L/SA:H |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
ActiveConfidentiality
NoneIntegrity
LowAvailability
LowSub Conf.
NoneSub Integrity
LowSub Availability
HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:L/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/MISP/MISP/commit/f82646727 | 5a6e4751-2f3f-4070-9419-94fb35b644e8 | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Andras Iklody (en)
CNA: Scottish Government - National Cyber Team (en)
CNA: Peter James (en)
There are currently no legacy QID mappings associated with this CVE.