CVE-2023-6937— Improper (D)TLS key boundary enforcement
Quick assessment
Affected
wolfSSL wolfSSL
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
wolfSSL（CyaSSL）是美国wolfSSL公司的一个针对嵌入式系统开发人员使用的小的、可移植的嵌入式SSL编程库。 WolfSSL 5.6.6之前版本存在安全漏洞，该漏洞源于不会检查消息是否跨越密钥边界，攻击者可以将使用不同密钥的消息合并到一个记录中。
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I. Basic Information for CVE-2023-6937
Vulnerability Information
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Vulnerability Title
Improper (D)TLS key boundary enforcement
Source: CVE Program / CVE List V5
Vulnerability Description
wolfSSL prior to 5.6.6 did not check that messages in one (D)TLS record do not span key boundaries. As a result, it was possible to combine (D)TLS messages using different keys into one (D)TLS record. The most extreme edge case is that, in (D)TLS 1.3, it was possible that an unencrypted (D)TLS 1.3 record from the server containing first a ServerHello message and then the rest of the first server flight would be accepted by a wolfSSL client. In (D)TLS 1.3 the handshake is encrypted after the ServerHello but a wolfSSL client would accept an unencrypted flight from the server. This does not compromise key negotiation and authentication so it is assigned a low severity rating.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
wolfSSL 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
wolfSSL（CyaSSL）是美国wolfSSL公司的一个针对嵌入式系统开发人员使用的小的、可移植的嵌入式SSL编程库。 WolfSSL 5.6.6之前版本存在安全漏洞，该漏洞源于不会检查消息是否跨越密钥边界，攻击者可以将使用不同密钥的消息合并到一个记录中。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2023-6937
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Patches & Fixes for CVE-2023-6937 (1)
Vendor Pages for CVE-2023-6937 (1)
IV. Related Vulnerabilities
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Same vendor: wolfSSL
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Same weakness: CWE-20
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CVE-2026-48378
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CVE-2026-100120
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V. Comments for CVE-2023-6937
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