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Fencer Intel
high 8.3

CVE-2026-103321 json

MISP Stored Cross-Site Scripting (XSS) via Unvalidated Event Graph Preview Image

published last mo. modified last mo. also EUVD-2026-89800

cvss
8.3
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 script (XSS) vulnerability in the event graph preview feature.

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's src attribute via string concatenation, allowing a crafted value to break out of the attribute context and inject arbitrary script.

Preconditions:

- An authenticated MISP user with the ability to create or modify an event graph entry.

- A second user (the victim) who views the event graph and triggers the preview popover.

Impact:

- Execution of arbitrary JavaScript in the victim's browser within the MISP application context.

- Potential theft of session tokens, cookies, or sensitive data accessible to the victim's browser.

- Potential for performing actions on behalf of the victim within the MISP application.

Affected: MISP versions prior to the fix (commit applied after v2.5.48).

Patch / fix

  • MISP MISP 2.5.48

Is CVE-2026-103321 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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 8.3 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
CNA 4.0 8.3 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/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
  • CWE-20 Improper Input Validation

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.