MISP Event Template Instantiation Bypasses Sharing Group and Tagging Authorization

published 2026-09-10 1 mo ago modified 2026-09-10 59 d ago also EUVD-2026-75409

cvss: 7.1; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 28%
public exploits: 0; none known

Affected versions of MISP do not consistently enforce the acting user's authorization when instantiating event templates.

For templates using distribution = 4, the template can specify a sharing_group_id. The instantiation path passed that value into event creation without verifying that the user instantiating the template was actually permitted to use the selected sharing group. The commit notes that Event::_add() only performed its own sharing-group authorization in another code path, leaving template instantiation able to write the identifier directly.

The same instantiation path also attached template-specified tags without checking the user's normal tagging permissions. In addition, it hardcoded local => 0, meaning tags marked local_only could be attached globally and consequently propagate through synchronization or export, contrary to their intended restriction.

The fix adds explicit SharingGroup::canUse() authorization for the acting user, applies the same tag-modification checks used by normal event tagging, and ensures local_only tags are attached locally.

Version affected: ≤2.5.45

Patch / fix

links 1

github.com/MISP/MISP@3aa3a9a commit

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 59 d ago (2026-09-10)

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	7.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CNA	4.0	7.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/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

Affected products

MISP MISP

Classification

Weakness

CWE-862 Missing Authorization

References

github.com /MISP/MISP/commit/3aa3a9a97
patch

Sources

CVE List CVE-2026-88915
NVD CVE-2026-88915

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary