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CVE-2023-6935: Marvin Attack vulnerability in SP Math All RSA

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-02-09 · updated 2026-06-17
• Weakness: CWE-203

Description

wolfSSL SP Math All RSA implementation is vulnerable to the Marvin Attack, new variation of a timing Bleichenbacher style attack, when built with the following options to configure: --enable-all CFLAGS="-DWOLFSSL_STATIC_RSA" The define “WOLFSSL_STATIC_RSA” enables static RSA cipher suites, which is not recommended, and has been disabled by default since wolfSSL 3.6.6.  Therefore the default build since 3.6.6, even with "--enable-all", is not vulnerable to the Marvin Attack. The vulnerability is specific to static RSA cipher suites, and expected to be padding-independent. The vulnerability allows an attacker to decrypt ciphertexts and forge signatures after probing with a large number of test observations. However the server’s private key is not exposed.

Affected products

• wolfSSL: from 3.12.2 through 5.6.4

References

• https://people.redhat.com/~hkario/marvin/
• https://www.wolfssl.com/docs/security-vulnerabilities/
• https://people.redhat.com/~hkario/marvin/
• https://www.wolfssl.com/docs/security-vulnerabilities/

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