CVE-2021-28681Public exploitNetwork attack vector

Authentication bypass via unclosed failed DTLS connection

Published Mar 18, 2021 · Updated Aug 3, 2024

Authorization bypass in Pion WebRTC before 3.0.15 allows remote attackers to establish data channels with an invalid DTLS certificate. DTLSTransport.Start sets PeerConnectionState to failed after fingerprint verification fails but leaves the DTLS connection usable instead of closing it. Attackers must know the ICE password and act during the PeerConnection handshake; applications that ignore the failed state can then exchange data with the unverified peer.

CVSS severity5.3
Medium
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Pion WebRTC before 3.0.15 allows remote attackers to establish data channels with an invalid DTLS certificate. DTLSTransport.Start sets PeerConnectionState to failed after fingerprint verification fails but leaves the DTLS connection usable instead of closing it. Attackers must know the ICE password and act during the PeerConnection handshake; applications that ignore the failed state can then exchange data with the unverified peer.

The record

CVE
CVE-2021-28681
Published
Mar 18, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-863, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 18, 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?

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

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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-863Incorrect Authorization
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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