MISP contains a reflected cross-site scripting (XSS) vulnerability in the event REST search export confirmation form. The view template app/View/Events/ajax/eventRestSearchExportConfirmationForm.ctp renders a URL-supplied event ID list into a single-quoted JavaScript string literal using PHP's json_encode() without any hex-encoding flags. By default, json_encode() escapes double quotes and backslashes but does not escape single quotes. Because the JavaScript string is delimited by single quotes, an attacker can inject a single-quote character to terminate the string literal and execute arbitrary JavaScript in the victim's browser session.
The vulnerability affects the Default and UiBeta themes, both of which render this view. The Overmind theme's own copy of the form already passed the value through an escaped data attribute and was not affected by this specific sink.
Preconditions: the victim must be an authenticated MISP user and must actively open or navigate to the attacker-crafted URL. The attacker does not require an account or any prior access to the MISP instance.
Security impact: successful exploitation allows execution of arbitrary JavaScript in the context of the MISP web application, potentially leading to session hijacking, unauthorized actions performed on behalf of the victim, exfiltration of sensitive data visible in the session, or further client-side attacks. The vulnerable component's own confidentiality, integrity, and availability are not directly compromised; the impact is on the underlying user session.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.1): severity, escalated by confirmed exploitation. This CVE's 5.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.1 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it