Internal network probing via unrestricted WebRTC ports
Published Mar 31, 2021 · Updated Aug 3, 2024
WebRTC port-filter bypass in Firefox before 87, Firefox ESR before 78.9, and Thunderbird before 78.9 allows remote attackers to probe internal hosts. The WebRTC networking code omitted Necko's existing outgoing-port block list, allowing page-controlled connections to reach normally restricted ports. Exploitation requires a user to load a malicious webpage and reveals the reachability of internal hosts and local services.
Summary
What happened
WebRTC port-filter bypass in Firefox before 87, Firefox ESR before 78.9, and Thunderbird before 78.9 allows remote attackers to probe internal hosts. The WebRTC networking code omitted Necko's existing outgoing-port block list, allowing page-controlled connections to reach normally restricted ports. Exploitation requires a user to load a malicious webpage and reveals the reachability of internal hosts and local services.
The record
- CVE
- CVE-2021-23982
- Published
- Mar 31, 2021
- Updated
- Aug 3, 2024
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-326, T1595.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 31, 2021CVE publishedPublication date reported by the CVE source.
- 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.
- Affected versionversion=unspecified <87
What conditions does exploitation require?
What is affected?
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.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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