CVE-2021-29451Public exploitNetwork attack vector

Authentication bypass via acceptance of unsigned JWTs

Published Apr 16, 2021 · Updated Aug 3, 2024

Improper JWT signature verification in ManyDesigns Portofino before 5.2.1 allows remote attackers to bypass authentication. JWTRealm and AbstractPortofinoRealm call JJWT's generic parse method, which accepts a two-part unsigned token instead of requiring parseClaimsJws. No credentials or user interaction are required; a forged token supplies attacker-chosen claims and gains the access assigned to the impersonated principal.

CVSS severity9.1
Critical
EPSS probability0.95%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper JWT signature verification in ManyDesigns Portofino before 5.2.1 allows remote attackers to bypass authentication. JWTRealm and AbstractPortofinoRealm call JJWT's generic parse method, which accepts a two-part unsigned token instead of requiring parseClaimsJws. No credentials or user interaction are required; a forged token supplies attacker-chosen claims and gains the access assigned to the impersonated principal.

The record

CVE
CVE-2021-29451
Published
Apr 16, 2021
Updated
Aug 3, 2024
Vendor
ManyDesigns
Product
Portofino
Classifications
CWE-347, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 16, 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=>= 5.0.0, < 5.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ManyDesigns · Portofinoversion=>= 5.0.0, < 5.2.1

Published CVSS scores

6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N
9.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1190Exploit Public-Facing Application

Public exploit references

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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