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CVE-2023-6936
Heap-buffer over-read with WOLFSSL_CALLBACKS
Medium5.3EPSS 0.60%
- Published
- Updated
- Reserved
- Assigned by
- wolfSSL
Description
In wolfSSL prior to 5.6.6, if callback functions are enabled (via the WOLFSSL_CALLBACKS flag), then a malicious TLS client or network attacker can trigger a buffer over-read on the heap of 5 bytes (WOLFSSL_CALLBACKS is only intended for debugging).
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| wolfSSLCNA (assigner) | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| NVDNVD · Modified | 3.1 | Critical9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.60% · top 51% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
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The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Weakness
Affected products
What to do
Solution: The fix for this issue is located in the following GitHub Pull Request: https://github.com/wolfSSL/wolfssl/pull/6949/ https://github.com/wolfSSL/wolfssl/pull/6949/
Workaround: * Do not build wolfSSL with WOLFSSL_CALLBACKS defined
References (2)
- https://github.com/wolfSSL/wolfssl/pull/6949/ (opens in a new tab)patchx_transferred
- https://www.wolfssl.com/docs/security-vulnerabilities/ (opens in a new tab)vendor-advisoryx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-6936)Record last updated .