CVE-2023-4807: POLY1305 MAC implementation corrupts XMM registers on Windows
Issue summary: The POLY1305 MAC (message authentication code) implementation contains a bug that might corrupt the internal state of applications on the Windows 64 platform when running on newer X8664 processors supporting the AVX512-IFMA instructions.
Impact summary: If in an application that uses the OpenSSL library an attacker can influence whether the POLY1305 MAC algorithm is used, the application state might be corrupted with various application dependent consequences.
The POLY1305 MAC (message authentication code) implementation in OpenSSL does not save the contents of non-volatile XMM registers on Windows 64 platform when calculating the MAC of data larger than 64 bytes. Before returning to the caller all the XMM registers are set to zero rather than restoring their previous content. The vulnerable code is used only on newer x8664 processors supporting the AVX512-IFMA instructions.
The consequences of this kind of internal application state corruption can be various - from no consequences, if the calling application does not depend on the contents of non-volatile XMM registers at all, to the worst consequences, where the attacker could get complete control of the application process. However given the contents of the registers are just zeroized so the attacker cannot put arbitrary values inside, the most likely consequence, if any, would be an incorrect result of some application dependent calculations or a crash leading to a denial of service.
The POLY1305 MAC algorithm is most frequently used as part of the CHACHA20-POLY1305 AEAD (authenticated encryption with associated data) algorithm. The most common usage of this AEAD cipher is with TLS protocol versions 1.2 and 1.3 and a malicious client can influence whether this AEAD cipher is used by the server. This implies that server applications using OpenSSL can be potentially impacted. However we are currently not aware of any concrete application that would be affected by this issue therefore we consider this a Low severity security issue.
As a workaround the AVX512-IFMA instructions support can be disabled at runtime by setting the environment variable OPENSSLia32cap:
OPENSSLia32cap=:~0x200000
The FIPS provider is not affected by this issue.
Other sources
OpenSSL is vulnerable to a denial of service, caused by a state corruption flaw in the POLY1305 MAC (message authentication code) implementation, when running on newer X8664 processors supporting the AVX512-IFMA instructions. A local authenticated attacker could exploit this vulnerability to cause an incorrect result of some application dependent calculations or a crash or in some cases gain complete control of the application process.
— IBM
POLY1305 MAC implementation corrupts XMM registers on Windows
— Microsoft
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the vulnerability ID?
The vulnerability ID is CVE-2023-4807.
What is the severity of CVE-2023-4807?
The severity of CVE-2023-4807 is high with a CVSS score of 7.8.
Which software is affected by CVE-2023-4807?
OpenSSL versions 1.1.1 to 1.1.1w, OpenSSL versions 3.0.0 to 3.0.11, and OpenSSL versions 3.1.0 to 3.1.3 are affected by CVE-2023-4807.
What is the impact of CVE-2023-4807?
CVE-2023-4807 can corrupt the internal state of applications on the Windows 64 platform running on newer X86_64 processors that support AVX512-IFMA instructions.
How do I fix CVE-2023-4807?
To fix CVE-2023-4807, users should update to the latest version of OpenSSL that includes the necessary patches.