CVE-2020-15084Network attack vector

Authorization bypass via missing algorithm allowlist

Published Jun 30, 2020 · Updated Aug 4, 2024

Improper authorization in Auth0 express-jwt 5.3.3 and earlier allows remote attackers to bypass JWT-based access controls. The middleware accepts verification options without an enforced algorithm allowlist, allowing jwks-rsa-selected keys to validate tokens under unintended algorithms. Exposure requires an omitted algorithms option and a callback secret such as jwks-rsa; accepted tokens receive the protected route's configured access.

CVSS severity9.1
Critical
EPSS probability1.05%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in Auth0 express-jwt 5.3.3 and earlier allows remote attackers to bypass JWT-based access controls. The middleware accepts verification options without an enforced algorithm allowlist, allowing jwks-rsa-selected keys to validate tokens under unintended algorithms. Exposure requires an omitted algorithms option and a callback secret such as jwks-rsa; accepted tokens receive the protected route's configured access.

The record

CVE
CVE-2020-15084
Published
Jun 30, 2020
Updated
Aug 4, 2024
Vendor
Auth0
Product
express-jwt
Classifications
CWE-285, CWE-863, T1606
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 30, 2020CVE 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=<= 5.3.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Auth0 · express-jwtversion=<= 5.3.3

Published CVSS scores

7.7GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
9.1NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
4.3NISTAV: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-285Improper Authorization
CWE-863Incorrect Authorization
T1606Forge Web Credentials

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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