CVE-2026-3951Public exploitNetwork attack vector

Browser script execution via unencoded error response

Published Mar 11, 2026 · Updated Mar 11, 2026

Reflected XSS in Locker 0.0.0, 0.0.1, and 0.1.0 allows remote attackers to execute JavaScript via a crafted auth ID. The authIsAwesome function concatenates req.params.id directly into a res.send error body without sanitization or output encoding. A victim must open the crafted /auth/:id URL; the payload then runs in that victim's browser in the Locker origin.

CVSS severity4.3
Medium
EPSS probability0.30%
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 Locker 0.0.0, 0.0.1, and 0.1.0 allows remote attackers to execute JavaScript via a crafted auth ID. The authIsAwesome function concatenates req.params.id directly into a res.send error body without sanitization or output encoding. A victim must open the crafted /auth/:id URL; the payload then runs in that victim's browser in the Locker origin.

The record

CVE
CVE-2026-3951
Published
Mar 11, 2026
Updated
Mar 11, 2026
Vendor
The Locker Project
Product
Locker
Classifications
CWE-79, CWE-94, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 11, 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=0.0.0
  2. Affected versionversion=0.0.1
  3. Affected versionversion=0.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Locker Project · Lockerversion=0.0.0; version=0.0.1; version=0.1.0

Published CVSS scores

5.0VulDBAV:N/AC:L/Au:N/C:N/I:P/A:N
5.3VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
4.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A: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 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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-94Improper Control of Generation of Code ('Code Injection')
T1204.001Malicious Link

Public exploit references

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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