CVE-2026-66824Network attack vector

Stored XSS via inline capture tree JSON

Published Jul 27, 2026 · Updated Jul 27, 2026

Stored cross-site scripting in Lookyloo 1.40.0 and earlier allows remote attackers to execute JavaScript when a user views a captured tree. The capture tree template applies the Jinja safe filter to serialized capture data and inserts it into an inline script, so a crafted value can close the script element and inject executable markup. The attacker needs capture data derived from controlled web content and a user to open the affected tree; injected code then acts with that user’s application permissions and can read or modify accessible data.

CVSS severity9.2
Critical
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Lookyloo 1.40.0 and earlier allows remote attackers to execute JavaScript when a user views a captured tree. The capture tree template applies the Jinja safe filter to serialized capture data and inserts it into an inline script, so a crafted value can close the script element and inject executable markup. The attacker needs capture data derived from controlled web content and a user to open the affected tree; injected code then acts with that user’s application permissions and can read or modify accessible data.

The record

CVE
CVE-2026-66824
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
Lookyloo
Product
Lookyloo
Classifications
CWE-79, CAPEC-592, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 27, 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 <=1.40.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Lookyloo · Lookylooversion=0 <=1.40.0

Published CVSS scores

9.2CIRCLCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')
CAPEC-592Stored XSS
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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