Heap over-read via misapplied callback offset
Published Feb 20, 2024 · Updated Mar 26, 2025
Heap-buffer over-read in wolfSSL before 5.6.6 allows remote attackers to read five bytes past a heap buffer via a malformed TLS 1.3 ClientHello. The callback packet-capture path in src/internal.c applies the late record-layer offset to the memcpy source rather than its destination, so tracing reads beyond the received data. Only TLS 1.3 server builds compiled with optional WOLFSSL_CALLBACKS are exposed; the flag is intended solely for debugging, and the reported impact is limited to a five-byte heap read.
Summary
What happened
Heap-buffer over-read in wolfSSL before 5.6.6 allows remote attackers to read five bytes past a heap buffer via a malformed TLS 1.3 ClientHello. The callback packet-capture path in src/internal.c applies the late record-layer offset to the memcpy source rather than its destination, so tracing reads beyond the received data. Only TLS 1.3 server builds compiled with optional WOLFSSL_CALLBACKS are exposed; the flag is intended solely for debugging, and the reported impact is limited to a five-byte heap read.
The record
- CVE
- CVE-2023-6936
- Published
- Feb 20, 2024
- Updated
- Mar 26, 2025
- Vendor
- wolfSSL
- Product
- wolfSSL
- Classifications
- T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 20, 2024CVE publishedPublication date reported by the CVE source.
- Mar 26, 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?
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- Affected versionversion=0 <=5.6.5
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What is affected?
Published CVSS scores
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Attacks
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Technologies
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Your stack
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