Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-103321

Severity CVSS v4.0:
HIGH
Type:
CWE-20 Input Validation
Publication date:
30/09/2026
Last modified:
30/09/2026

Description

MISP contains a stored cross-site script (XSS) vulnerability in the event graph preview feature.<br /> <br /> The event graph preview image field was accepted and stored without server-side validation. On the client side, the stored value was rendered into an HTML img element&amp;#39;s src attribute via string concatenation, allowing a crafted value to break out of the attribute context and inject arbitrary script.<br /> <br /> Preconditions:<br /> <br /> - An authenticated MISP user with the ability to create or modify an event graph entry.<br /> <br /> - A second user (the victim) who views the event graph and triggers the preview popover.<br /> <br /> Impact:<br /> <br /> - Execution of arbitrary JavaScript in the victim&amp;#39;s browser within the MISP application context.<br /> <br /> - Potential theft of session tokens, cookies, or sensitive data accessible to the victim&amp;#39;s browser.<br /> <br /> - Potential for performing actions on behalf of the victim within the MISP application.<br /> <br /> Affected: MISP versions prior to the fix (commit applied after v2.5.48).

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 8.30 HIGH
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): Low
User Interaction (UI): Passsive
Confidentiality (VC): None
Integrity (VI): High
Availability (VA): None
Confidentiality (SC): High
Integrity (SI): High
Availability (SA): None

Base Score 4.0
8.30
Severity 4.0
HIGH

References to Advisories, Solutions, and Tools