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CVE-2021-32641

Reflected XSS when using flashMessages

8.1 HighFix available

auth0-lock is Auth0's signin solution. Versions of nauth0-lock before and including 11.30.0 are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's flashMessage feature is utilized and user input or data from URL parameters is incorporated into the flashMessage or the library's languageDictionary feature is utilized and user input or data from URL parameters is incorporated into the languageDictionary. The vulnerability is patched in version 11.30.1.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.54%Up 0.1 points since Jun 5, 2021
90%50%10%1%

What each source reports

CVE List Score used 8.1

Reflected XSS when using flashMessages

auth0-lock is Auth0's signin solution. Versions of nauth0-lock before and including 11.30.0 are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's flashMessage feature is utilized and user input or data from URL parameters is incorporated into the flashMessage or the library's languageDictionary feature is utilized and user input or data from URL parameters is incorporated into the languageDictionary. The vulnerability is patched in version 11.30.1.

Record
CVE-2021-32641
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-79
Updated
2026-11-02
EUVDEUVD-2021-1348 8.1

auth0-lock is Auth0's signin solution. Versions of nauth0-lock before and including 11.30.0 are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's flashMessage feature is utilized and user input or data from URL parameters is incorporated into the flashMessage or the library's languageDictionary feature is utilized and user input or data from URL parameters is incorporated into the languageDictionary. The vulnerability is patched in version 11.30.1.

Record
EUVD-2021-1348
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-jr3j-whm4-9wwm 8.1

Reflected XSS when using flashMessages or languageDictionary

Overview

Versions before and including 11.30.0 are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's

  • flashMessage feature is utilized and user input or data from URL parameters is incorporated into the flashMessage.
  • languageDictionary feature is utilized and user input or data from URL parameters is incorporated into the languageDictionary.

Am I affected?

You are affected by this vulnerability if you are using auth0-lock version 11.30.0 or lower and all of the following conditions apply:

  • You are utilizing flashMessage feature.
  • User input or data from URL parameters is incorporated into the flashMessage.

An example of a vulnerable snippet where query parameters are used to populate the text property of a flashMessage.

var params = new URLSearchParams(location.search);
var errorMessage = params.get('error__message');
var showParams = {};

if (!!errorMessage === true) {
  showParams.flashMessage = {
    type: 'error',
    text: 'We were unable to log you in. ' + errorMessage,
  };
}

lock.show(showParams);

OR

  • You are utilizing languageDictionary feature.
  • User input or data from URL parameters is used in languageDictionary properties.

An example of a vulnerable snippet where query parameters are used to populate the socialLoginInstructions property of a languageDictionary.

var params = new URLSearchParams(location.search);
var instruction = params.get('instruction');

var options = {
  languageDictionary: {
    emailInputPlaceholder: "[email protected]",
    title: "title",
    socialLoginInstructions: instruction
  },
};

var lock = new Auth0LockPasswordless(
    CLIENT_ID,
    DOMAIN,
    options
);

lock.show()

How to fix that?

Upgrade to version 11.30.1.

Will this update impact my users?

The fix uses DOMPurify to sanitise the flashMessage and languageDictionary inputs. If you are including inline JavaScript in these fields, like script tags or onclick attributes, these will be removed.

Record
GHSA-jr3j-whm4-9wwm
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-79
Updated
2026-11-02
NVD 8.1

auth0-lock is Auth0's signin solution. Versions of nauth0-lock before and including 11.30.0 are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's flashMessage feature is utilized and user input or data from URL parameters is incorporated into the flashMessage or the library's languageDictionary feature is utilized and user input or data from URL parameters is incorporated into the languageDictionary. The vulnerability is patched in version 11.30.1.

Record
CVE-2021-32641
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:N/I:P/A:N
Weakness
CWE-79
Updated
2026-11-02
OSV 6.1

auth0-lock is Auth0's signin solution. Versions of nauth0-lock before and including 11.30.0 are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's flashMessage feature is utilized and user input or data from URL parameters is incorporated into the flashMessage or the library's languageDictionary feature is utilized and user input or data from URL parameters is incorporated into the languageDictionary. The vulnerability is patched in version 11.30.1.

Record
CVE-2021-32641
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVGHSA-jr3j-whm4-9wwm 8.1

Reflected XSS when using flashMessages or languageDictionary

Overview

Versions before and including 11.30.0 are vulnerable to reflected XSS. An attacker can execute arbitrary code when the library's

  • flashMessage feature is utilized and user input or data from URL parameters is incorporated into the flashMessage.
  • languageDictionary feature is utilized and user input or data from URL parameters is incorporated into the languageDictionary.

Am I affected?

You are affected by this vulnerability if you are using auth0-lock version 11.30.0 or lower and all of the following conditions apply:

  • You are utilizing flashMessage feature.
  • User input or data from URL parameters is incorporated into the flashMessage.

An example of a vulnerable snippet where query parameters are used to populate the text property of a flashMessage.

var params = new URLSearchParams(location.search);
var errorMessage = params.get('error__message');
var showParams = {};

if (!!errorMessage === true) {
  showParams.flashMessage = {
    type: 'error',
    text: 'We were unable to log you in. ' + errorMessage,
  };
}

lock.show(showParams);

OR

  • You are utilizing languageDictionary feature.
  • User input or data from URL parameters is used in languageDictionary properties.

An example of a vulnerable snippet where query parameters are used to populate the socialLoginInstructions property of a languageDictionary.

var params = new URLSearchParams(location.search);
var instruction = params.get('instruction');

var options = {
  languageDictionary: {
    emailInputPlaceholder: "[email protected]",
    title: "title",
    socialLoginInstructions: instruction
  },
};

var lock = new Auth0LockPasswordless(
    CLIENT_ID,
    DOMAIN,
    options
);

lock.show()

How to fix that?

Upgrade to version 11.30.1.

Will this update impact my users?

The fix uses DOMPurify to sanitise the flashMessage and languageDictionary inputs. If you are including inline JavaScript in these fields, like script tags or onclick attributes, these will be removed.

Record
GHSA-jr3j-whm4-9wwm
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-79
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
auth0-lock
npm
before 11.30.1
11.30.1

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-32641 is a high vulnerability (CVSS 8.1) in Auth0 Lock, published June 4, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.54%, the 75th percentile. Fixed in auth0-lock 11.30.1.

References

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