CVE-2021-29500Public exploitNetwork attack vector

Authentication bypass via unsigned JWT acceptance

Published Jun 4, 2021 · Updated Aug 3, 2024

Improper JWT signature verification in fxbin Bubble Fireworks before 2021.BUILD-SNAPSHOT allows remote attackers to forge valid tokens. The SingleJwt and DoubleJwt parsers call JwtParser.parse, which accepts two-part JWTs with no signature instead of requiring a signed JWS. No authentication or user interaction is required; accepting a forged token can bypass application authentication and alter protected state.

CVSS severity7.5
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper JWT signature verification in fxbin Bubble Fireworks before 2021.BUILD-SNAPSHOT allows remote attackers to forge valid tokens. The SingleJwt and DoubleJwt parsers call JwtParser.parse, which accepts two-part JWTs with no signature instead of requiring a signed JWS. No authentication or user interaction is required; accepting a forged token can bypass application authentication and alter protected state.

The record

CVE
CVE-2021-29500
Published
Jun 4, 2021
Updated
Aug 3, 2024
Vendor
fxbin
Product
Bubble Fireworks
Classifications
CWE-347, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2021.BUILD-SNAPSHOT

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

fxbin · Bubble Fireworksversion=< 2021.BUILD-SNAPSHOT

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
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 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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo