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Fencer Vulns
medium 6.1

CVE-2026-54397 json

MISP event editing allows unauthorized assignment to undisclosed sharing groups

published 2026-06-12 4 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-36577

cvss
6.1
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

A vulnerability in MISP’s non-REST event editing path allowed an authenticated user with event edit permissions to manipulate the submitted form data and set an event’s sharing_group_id to a sharing group they were not authorized to use. When distribution was set to sharing group distribution, the non-REST save path accepted the submitted sharing_group_id without performing the same sharing group authorization check enforced by the REST edit path.

An attacker could exploit this by tampering with the event edit request and assigning an event to an undisclosed or unauthorized sharing group. This could result in unauthorized use of restricted sharing groups, disclosure of the sharing group name in event listings, and unintended modification of the event’s distribution metadata.

The issue is fixed by validating that the selected sharing group can be used by the current user when the sharing group is changed, and by clearing sharing_group_id when the event distribution is not set to sharing group distribution.

Patch / fix

  • misp misp 2.5.40

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:H/SI:N/SA:N
CNA 4.0 6.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:H/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

References

Sources

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.