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Fencer Intel
medium 5.3

CVE-2026-104900 json

MISP Stored XSS via Unescaped Count Field Value in Remote Event Preview Index

published last mo. modified last mo. also EUVD-2026-91669

cvss
5.3
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 29%
public exploits
0
none known

Summary

MISP contains a stored cross-site scripting (XSS) vulnerability in the index table rendering of the remote event preview. The count field template escaped the associated link URL but rendered the field value without HTML encoding. An attacker with the ability to create or modify events on a linked (remote) MISP server could craft an event identifier containing HTML or JavaScript markup. When a user on the local MISP instance views the remote event preview index, the unescaped value is rendered directly in the browser, allowing arbitrary script execution in the victim's session.

Preconditions:

- A linked/remote MISP server is configured and connected to the local instance.

- The attacker has sufficient access on the linked server to create or modify an event with a crafted identifier.

- A victim user on the local instance views the remote event preview index page.

Impact:

- Execution of arbitrary JavaScript in the context of the MISP web application.

- Potential session hijacking, data exfiltration, or unauthorized actions performed on behalf of the authenticated user.

Affected versions: <2.5.48.

Patch / fix

  • MISP MISP 2.5.48

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/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-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel 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.