CVE-2021-44878Network attack vector

Authentication bypass via accepted unsigned ID tokens

Published Jan 6, 2022 · Updated Aug 4, 2024

Authentication bypass in pac4j-oidc before 4.5.5 and 5.0 through 5.3.0 allows remote attackers to forge accepted ID tokens. TokenValidator builds an IDTokenValidator for the provider-advertised none algorithm without requiring allowUnsignedIdTokens, so an empty signature passes validation. Exploitation requires an OIDC provider that advertises none; the accepted forged token lets an unauthenticated attacker impersonate an authenticated identity.

CVSS severity7.5
High
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in pac4j-oidc before 4.5.5 and 5.0 through 5.3.0 allows remote attackers to forge accepted ID tokens. TokenValidator builds an IDTokenValidator for the provider-advertised none algorithm without requiring allowUnsignedIdTokens, so an empty signature passes validation. Exploitation requires an OIDC provider that advertises none; the accepted forged token lets an unauthenticated attacker impersonate an authenticated identity.

The record

CVE
CVE-2021-44878
Published
Jan 6, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, T1606
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 6, 2022CVE 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
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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