Traffic disclosure and modification via unbound master secrets
Published Feb 12, 2021 · Updated Aug 3, 2024
TLS session weakness in F5 Networks BIG-IP 11.6.x and 12.1.x allows man-in-the-middle attackers to read or modify renegotiated traffic. The original TLS master-secret calculation does not bind the secret to the full handshake, allowing synchronized sessions to share key material. Exploitation requires a network position between the peers, TLS renegotiation, and a connection that does not negotiate Extended Master Secret.
Summary
What happened
TLS session weakness in F5 Networks BIG-IP 11.6.x and 12.1.x allows man-in-the-middle attackers to read or modify renegotiated traffic. The original TLS master-secret calculation does not bind the secret to the full handshake, allowing synchronized sessions to share key material. Exploitation requires a network position between the peers, TLS renegotiation, and a connection that does not negotiate Extended Master Secret.
The record
- CVE
- CVE-2021-22981
- Published
- Feb 12, 2021
- Updated
- Aug 3, 2024
- Vendor
- F5 Networks
- Product
- BIG-IP
- Classifications
- T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 12, 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=All versions of 12.1.x and 11.6.x
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.
Weakness, pattern, technique
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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