CVE-2021-28681

In github.com/pion/webrtc, failed DTLS certificate verification doesn't stop data channel communication

Workarounds

Users should listen for when PeerConnectionState changes to PeerConnectionStateFailed. When it enters this state users should not continue using the PeerConnection.

For more information

If you have any questions or comments about this advisory:

• Open an issue in https://github.com/pion/webrtc
• Email us at [email protected]

Thank you to https://github.com/Gaukas for discovering this.

Data channel communication was incorrectly allowed with users who have failed DTLS certificate verification.

This attack requires

• Attacker knows the ICE password.
• Only take place during PeerConnection handshake.

This attack can be detected by monitoring PeerConnectionState in all versions of Pion WebRTC.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2021-28681 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.0.15); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

Users should upgrade to v3.0.15.

The exact patch is https://github.com/pion/webrtc/commit/545613dcdeb5dedb01cce94175f40bcbe045df2e

1. What is CVE-2021-28681? CVE-2021-28681 is a medium-severity incorrect authorization vulnerability in github.com/pion/webrtc/v3 (go), affecting versions < 3.0.15. It is fixed in 3.0.15. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2021-28681? CVE-2021-28681 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/pion/webrtc/v3 are affected by CVE-2021-28681? github.com/pion/webrtc/v3 (go) versions < 3.0.15 is affected.
4. Is there a fix for CVE-2021-28681? Yes. CVE-2021-28681 is fixed in 3.0.15. Upgrade to this version or later.
5. Is CVE-2021-28681 exploitable, and should I be worried? Whether CVE-2021-28681 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-28681 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-28681? Upgrade github.com/pion/webrtc/v3 to 3.0.15 or later.