Plaintext handshake disclosure via crossed key boundaries
Published Feb 15, 2024 · Updated Apr 24, 2025
Improper input validation in wolfSSL before 5.6.6 allows remote attackers to expose part of a TLS 1.3 server flight in plaintext. The client record parser fails to ensure that handshake messages sharing one TLS or DTLS record remain within a single encryption-key boundary. A malicious server must combine ServerHello and the protected remainder of its first flight in one unencrypted record; key negotiation and authentication remain intact.
Summary
What happened
Improper input validation in wolfSSL before 5.6.6 allows remote attackers to expose part of a TLS 1.3 server flight in plaintext. The client record parser fails to ensure that handshake messages sharing one TLS or DTLS record remain within a single encryption-key boundary. A malicious server must combine ServerHello and the protected remainder of its first flight in one unencrypted record; key negotiation and authentication remain intact.
The record
- CVE
- CVE-2023-6937
- Published
- Feb 15, 2024
- Updated
- Apr 24, 2025
- Vendor
- wolfSSL
- Product
- wolfSSL
- Classifications
- CWE-20
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 15, 2024CVE publishedPublication date reported by the CVE source.
- Apr 24, 2025Record 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=0 <=5.64
- Affected versionversion=0 <=5.6.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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