Segmentation fault in SSL_check_chain (CVE-2020-1967)
Severity: High
Server or client applications that call the SSL_check_chain() function during or
after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a
result of incorrect handling of the "signature_algorithms_cert" TLS extension.
The crash occurs if an invalid or unrecognised signature algorithm is received
from the peer. This could be exploited by a malicious peer in a Denial of
Service attack.
OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This
issue did not affect OpenSSL versions prior to 1.1.1d.
Affected OpenSSL 1.1.1 users should upgrade to 1.1.1g
This issue was found by Bernd Edlinger and reported to OpenSSL on 7th April
It was found using the new static analysis pass being implemented in GCC,
-fanalyzer. Additional analysis was performed by Matt Caswell and Benjamin
Kaduk.
Note
This issue did not affect OpenSSL 1.0.2 however these versions are out of
support and no longer receiving public updates. Extended support is available
for premium support customers: https://www.openssl.org/support/contracts.html
This issue did not affect OpenSSL 1.1.0 however these versions are out of
support and no longer receiving updates.
Users of these versions should upgrade to OpenSSL 1.1.1.
*) Fixed segmentation fault in SSL_check_chain()
Server or client applications that call the SSL_check_chain() function
during or after a TLS 1.3 handshake may crash due to a NULL pointer
dereference as a result of incorrect handling of the
"signature_algorithms_cert" TLS extension. The crash occurs if an invalid
or unrecognised signature algorithm is received from the peer. This could
be exploited by a malicious peer in a Denial of Service attack.
(CVE-2020-1967)
[Benjamin Kaduk]
*) Added AES consttime code for no-asm configurations
an optional constant time support for AES was added
when building openssl for no-asm.
Enable with: ./config no-asm -DOPENSSL_AES_CONST_TIME
Disable with: ./config no-asm -DOPENSSL_NO_AES_CONST_TIME
At this time this feature is by default disabled.
It will be enabled by default in 3.0.
[Bernd Edlinger]
OpenSSL Security Advisory [21 April 2020]
Segmentation fault in SSL_check_chain (CVE-2020-1967)
Severity: High
Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signature_algorithms_cert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm is received from the peer. This could be exploited by a malicious peer in a Denial of Service attack.
OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This issue did not affect OpenSSL versions prior to 1.1.1d.
Affected OpenSSL 1.1.1 users should upgrade to 1.1.1g
This issue was found by Bernd Edlinger and reported to OpenSSL on 7th April
Note
This issue did not affect OpenSSL 1.0.2 however these versions are out of support and no longer receiving public updates. Extended support is available for premium support customers: https://www.openssl.org/support/contracts.html
This issue did not affect OpenSSL 1.1.0 however these versions are out of support and no longer receiving updates.
Users of these versions should upgrade to OpenSSL 1.1.1.
References
URL for this Security Advisory: https://www.openssl.org/news/secadv/20200421.txt
Changes between 1.1.1f and 1.1.1g [21 Apr 2020]
*) Fixed segmentation fault in SSL_check_chain() Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signature_algorithms_cert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm is received from the peer. This could be exploited by a malicious peer in a Denial of Service attack. (CVE-2020-1967) [Benjamin Kaduk]
*) Added AES consttime code for no-asm configurations an optional constant time support for AES was added when building openssl for no-asm. Enable with: ./config no-asm -DOPENSSL_AES_CONST_TIME Disable with: ./config no-asm -DOPENSSL_NO_AES_CONST_TIME At this time this feature is by default disabled. It will be enabled by default in 3.0. [Bernd Edlinger]