CVE-2021-32702Network attack vector

Reflected XSS via unescaped callback error

Published Jun 25, 2021 · Updated Aug 3, 2024

Reflected XSS in Auth0 Next.js SDK before 1.4.2 allows remote attackers to execute script through a crafted callback error query. The callback handler passes the OpenID Connect error parameter into an exception message that the default server-side error handler returns in HTML without escaping. Exploitation requires a user to follow a crafted callback URL and applies when the default error handler, rather than a custom handler that avoids rendering the message, is used.

CVSS severity8.0
High
EPSS probability1.40%
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 Auth0 Next.js SDK before 1.4.2 allows remote attackers to execute script through a crafted callback error query. The callback handler passes the OpenID Connect error parameter into an exception message that the default server-side error handler returns in HTML without escaping. Exploitation requires a user to follow a crafted callback URL and applies when the default error handler, rather than a custom handler that avoids rendering the message, is used.

The record

CVE
CVE-2021-32702
Published
Jun 25, 2021
Updated
Aug 3, 2024
Vendor
Auth0
Product
Auth0 Next.js SDK
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=< 1.4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Auth0 · Auth0 Next.js SDKversion=< 1.4.2

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
8.0GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/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 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 ('Cross-site Scripting')
T1189Drive-by Compromise

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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