CVE-2026-77115Network attack vector

Unauthenticated reflected XSS via unescaped UTM parameters

Published Aug 23, 2026 · Updated Aug 23, 2026

Reflected XSS in Brave Popup Builder before 0.8.6 allows remote attackers to execute script through crafted UTM parameters. The plugin copies UTM query values into popup form HTML without output escaping, so injected markup is interpreted by the visitor's browser. Exploitation requires a user to open the crafted URL and a popup form to consume the supplied UTM value; script then runs in the affected site's origin.

CVSS severity7.1
High
EPSS probability0.15%
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 Brave Popup Builder before 0.8.6 allows remote attackers to execute script through crafted UTM parameters. The plugin copies UTM query values into popup form HTML without output escaping, so injected markup is interpreted by the visitor's browser. Exploitation requires a user to open the crafted URL and a popup form to consume the supplied UTM value; script then runs in the affected site's origin.

The record

CVE
CVE-2026-77115
Published
Aug 23, 2026
Updated
Aug 23, 2026
Vendor
AmpleByte Pvt Limited
Product
Brave Popup Builder
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 23, 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 <0.8.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

AmpleByte Pvt Limited · Brave Popup Builderversion=0 <0.8.6

Published CVSS scores

7.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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