CVE-2026-54395Network attack vector

Authenticated reflected XSS via decoded handler input

Published Jun 12, 2026 · Updated Jun 12, 2026

Reflected XSS in the UiBeta event index in MISP before 2.5.40 allows remote authenticated users to execute browser JavaScript. The template places urlparams in a single-quoted inline onclick string after HTML escaping, so browser decoding restores quote characters from searcheventinfo before JavaScript parsing. Exploitation requires a victim to open the crafted URL while using UiBeta and exposes or modifies data available to that browser session.

CVSS severity5.3
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in the UiBeta event index in MISP before 2.5.40 allows remote authenticated users to execute browser JavaScript. The template places urlparams in a single-quoted inline onclick string after HTML escaping, so browser decoding restores quote characters from searcheventinfo before JavaScript parsing. Exploitation requires a victim to open the crafted URL while using UiBeta and exposes or modifies data available to that browser session.

The record

CVE
CVE-2026-54395
Published
Jun 12, 2026
Updated
Jun 12, 2026
Vendor
MISP Project
Product
MISP
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2.5.40

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

MISP Project · MISPversion=0 <2.5.40

Published CVSS scores

5.3CIRCLCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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