CVE-2023-4807

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 X86_64
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 x86_64
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 OPENSSL_ia32cap:
OPENSSL_ia32cap=:~0x200000 The FIPS provider is not affected by this issue.

Notes