CVE-2018-0732
HighCVSS 7.5Exploitation Probability (EPSS)
Very high risk99th percentile - higher than 99% of all known CVEs
Summary
During key agreement in a TLS handshake using a DH(E) based ciphersuite, a malicious server can send a very large prime value to the client. This causes the client to spend an unreasonably long period of time generating a key for this prime, resulting in a hang until the client has finished.
Risk Assessment
This could be exploited in a Denial of Service attack, blocking the client for an extended period and preventing normal communication.
Recommendation
Upgrade OpenSSL to version 1.1.0i-dev (for the 1.1.0 branch) or 1.0.2p-dev (for the 1.0.2 branch).
Other vulnerabilities in OpenSSL
See all- CVE-2016-8610High
A denial of service flaw was found in OpenSSL 0.9.8, 1.0.1, 1.0.2 through 1.0.2h, and 1.1.0 in the way the TLS/SSL protocol defined processing of ALERT packets during a connection handshake. A remote attacker could use this flaw to make a TLS/SSL server consume an excessive amount of CPU and fail to accept connections from other clients.
- CVE-2017-3731High
CVE-2017-3731 affects SSL/TLS servers and clients running on 32-bit hosts that may crash due to an out-of-bounds read caused by a truncated packet. For OpenSSL 1.1.0, the crash can be triggered using the CHACHA20/POLY1305 cipher, and for OpenSSL 1.0.2 using RC4-MD5.
- CVE-2017-3730High
In OpenSSL 1.1.0 before 1.1.0d, a malicious server can supply bad parameters for a DHE or ECDHE key exchange, leading to the client attempting to dereference a NULL pointer, resulting in a client crash.
- CVE-2016-7054High
In OpenSSL 1.1.0 before 1.1.0c, TLS connections using *-CHACHA20-POLY1305 ciphersuites are susceptible to a DoS attack by corrupting larger payloads. This can result in an OpenSSL crash.
- CVE-2016-7052High
OpenSSL 1.0.2i has a vulnerability that allows remote attackers to cause application crashes by triggering a CRL operation, leading to a NULL pointer dereference.
- CVE-2016-6305High
The ssl3_read_bytes function in OpenSSL 1.1.0 before version 1.1.0a allows remote attackers to cause a denial of service (infinite loop) by triggering a zero-length record in an SSL_peek call.
- CVE-2016-6304High
Multiple memory leaks in t1_lib.c in OpenSSL before 1.0.1u, 1.0.2 before 1.0.2i, and 1.1.0 before 1.1.0a allow remote attackers to cause a denial of service (memory consumption) via large OCSP Status Request extensions.
- CVE-2016-6302High
The tls_decrypt_ticket function in OpenSSL before 1.1.0 does not consider the HMAC size during validation of the ticket length, allowing remote attackers to cause a denial of service via a ticket that is too short.
- CVE-2016-2179High
The DTLS implementation in OpenSSL before 1.1.0 does not properly restrict the lifetime of queue entries associated with unused out-of-order messages. This allows remote attackers to cause a denial of service (memory consumption) by maintaining many crafted DTLS sessions simultaneously.
- CVE-2016-2176High
The X509_NAME_oneline function in OpenSSL before 1.0.1t and 1.0.2 before 1.0.2h allows remote attackers to obtain sensitive information from process stack memory or cause a denial of service (buffer over-read) via crafted EBCDIC ASN.1 data.
Original NVD description (English source)
During key agreement in a TLS handshake using a DH(E) based ciphersuite a malicious server can send a very large prime value to the client. This will cause the client to spend an unreasonably long period of time generating a key for this prime resulting in a hang until the client has finished. This could be exploited in a Denial Of Service attack. Fixed in OpenSSL 1.1.0i-dev (Affected 1.1.0-1.1.0h). Fixed in OpenSSL 1.0.2p-dev (Affected 1.0.2-1.0.2o).
Vulnerability data from NVD (NIST) · CISA KEV · EPSS