CVE-2021-39215Network attack vector

Authentication bypass via symmetric JWT algorithm confusion

Published Sep 15, 2021 · Updated Aug 4, 2024

Authentication bypass in Jitsi Meet before 2.0.5963 allows remote attackers to enter protected rooms with forged JSON Web Tokens. The Prosody token utility accepted a token-selected symmetric algorithm after loading a public key, causing that key to be reused as an HMAC verification secret. Exploitation requires token authentication with public-key retrieval enabled; a forged token grants room access without a trusted issuer's private key.

CVSS severity7.5
High
EPSS probability1.23%
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

Authentication bypass in Jitsi Meet before 2.0.5963 allows remote attackers to enter protected rooms with forged JSON Web Tokens. The Prosody token utility accepted a token-selected symmetric algorithm after loading a public key, causing that key to be reused as an HMAC verification secret. Exploitation requires token authentication with public-key retrieval enabled; a forged token grants room access without a trusted issuer's private key.

The record

CVE
CVE-2021-39215
Published
Sep 15, 2021
Updated
Aug 4, 2024
Vendor
Jitsi
Product
Jitsi Meet
Classifications
CWE-287, T1550.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 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

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=< 2.0.5963

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Jitsi · Jitsi Meetversion=< 2.0.5963

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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-287Improper Authentication
T1550.001Application Access Token

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

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