CVE-2021-41246Network attack vector

Session hijacking via unrotated login identifiers

Published Dec 9, 2021 · Updated Aug 4, 2024

Session fixation in Auth0 express-openid-connect 2.3.0 through 2.5.1 allows remote attackers to hijack authenticated sessions. The login callback reuses the existing custom-store session identifier and cookie instead of generating new values after authentication. A victim must authenticate through an application configured with a custom session store after an attacker has fixed a known session identifier, exposing the victim's session to takeover.

CVSS severity8.8
High
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session fixation in Auth0 express-openid-connect 2.3.0 through 2.5.1 allows remote attackers to hijack authenticated sessions. The login callback reuses the existing custom-store session identifier and cookie instead of generating new values after authentication. A victim must authenticate through an application configured with a custom session store after an attacker has fixed a known session identifier, exposing the victim's session to takeover.

The record

CVE
CVE-2021-41246
Published
Dec 9, 2021
Updated
Aug 4, 2024
Vendor
Auth0
Product
express-openid-connect
Classifications
CWE-384, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=>= 2.3.0, < 2.5.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Auth0 · express-openid-connectversion=>= 2.3.0, < 2.5.2

Published CVSS scores

6.8NISTAV:N/AC:M/Au:N/C:P/I:P/A:P
4.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
8.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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-384Session Fixation
T1550.004Web Session Cookie

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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