cbcvebase.
CVE-2020-1967
published 2020-04-21

CVE-2020-1967: 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…

PriorityP356high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
53.34%
98.9th percentile
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. Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f).

Affected

38 ranges· showing 25
VendorProductVersion rangeFixed in
debiandebian_linux
debiandebian_linux
debianopenssl< openssl 1.1.1g-1 (bookworm)openssl 1.1.1g-1 (bookworm)
fedoraprojectfedora
fedoraprojectfedora
fedoraprojectfedora
freebsdfreebsd
jdedwardsenterpriseone< 9.2.5.09.2.5.0
netappactive_iq_unified_manager>= 7.3
netappactive_iq_unified_manager>= 9.5
opensslopenssl
opensslopenssl>= 0 < 1.1.1g-11.1.1g-1
opensslopenssl>= 0 < 1.1.1g-11.1.1g-1
opensslopenssl>= 0 < 1.1.1g-11.1.1g-1
opensslopenssl>= 0 < 1.1.1g-11.1.1g-1
opensslopenssl1.1.1d – 1.1.1f
opensuseleap
opensuseleap
oracleapplication_server
oracleenterprise_manager_base_platform
oracleenterprise_manager_for_storage_management
oracleenterprise_manager_for_storage_management
oracleenterprise_manager_ops_center
oraclehttp_server
oraclejd_edwards_world_security

Detection & IOCsextracted from sources · hover to see the quote

  • Trigger condition: crash occurs when an invalid or unrecognised signature algorithm is received from the peer via the 'signature_algorithms_cert' TLS extension during or after a TLS 1.3 handshake, causing a NULL pointer dereference in SSL_check_chain()
  • Vulnerable code path: SSL_check_chain() is not called directly from libssl but may be invoked inside a callback (e.g., client_hello or cert callback); monitor for crashes/segfaults in OpenSSL-linked processes during TLS 1.3 negotiation
  • Scope limited to TLS 1.3 only; TLS 1.2 and earlier are not affected — filter TLS 1.3 handshake traffic for malformed signature_algorithms_cert extensions as a detection focus
  • A public PoC was published for this vulnerability; monitor for exploitation attempts against services using OpenSSL 1.1.1d–1.1.1f
  • ·Only OpenSSL versions 1.1.1d, 1.1.1e, and 1.1.1f are affected; versions prior to 1.1.1d are NOT vulnerable
  • ·Applications that do not invoke SSL_check_chain() are not vulnerable, even if compiled against an affected OpenSSL version
  • ·The flaw was introduced by a specific OpenSSL commit (5235ef44b93306a14d0b6c695b13c64b16e1fdec) shipped with OpenSSL 1.1.1d; patched in OpenSSL 1.1.1g

CVSS provenance

nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:N/I:N/A:P
osv7.5HIGH
vendor_debian7.5HIGH
vendor_oracle7.5HIGH
vendor_redhat7.5HIGH
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