CVE-2018-0733: Because of an implementation bug the PA-RISC CRYPTO_memcmp function is effectively reduced to only comparing the least significant bit of each byte. T...

Description

Because of an implementation bug the PA-RISC CRYPTO_memcmp function is effectively reduced to only comparing the least significant bit of each byte. This allows an attacker to forge messages that would be considered as authenticated in an amount of tries lower than that guaranteed by the security claims of the scheme. The module can only be compiled by the HP-UX assembler, so that only HP-UX PA-RISC targets are affected. Fixed in OpenSSL 1.1.0h (Affected 1.1.0-1.1.0g).

Metrics

EPSS Probability

8.61%

94.4th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Openssl	Openssl	>= 1.1.0, <= 1.1.0g

References

Timeline

Published: Mar 27, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-0733?

Because of an implementation bug the PA-RISC CRYPTO_memcmp function is effectively reduced to only comparing the least significant bit of each byte. This allows an attacker to forge messages that would be considered as authenticated in an amount of tries lower than that guaranteed by the security claims of the scheme. The module can only be compiled by the HP-UX assembler, so that only HP-UX PA-RISC targets are affected. Fixed in OpenSSL 1.1.0h (Affected 1.1.0-1.1.0g).

How severe is CVE-2018-0733?

Severity scoring for CVE-2018-0733 is pending analysis. The EPSS model estimates a 8.61% probability of exploitation in the next 30 days.

How do I fix CVE-2018-0733?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.