CVE-2019-1551: rsaz_512_sqr overflow bug on x86_64

Vulnerability summary

CVE-2019-1551 is a medium (CVSS 5.3) Integer Overflow or Wraparound vulnerability in canonical ubuntu_linux. EPSS estimates a 14.30% chance of exploitation in the next 30 days, higher than 96.6% of scored vulnerabilities.

Timeline

1. 06-12-2019
   PublishedVulnerability first disclosed.
2. 08-10-2026
   Last modifiedVulnerability information updated.

Description

There is an overflow bug in the x64_64 Montgomery squaring procedure used in exponentiation with 512-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against 2-prime RSA1024, 3-prime RSA1536, and DSA1024 as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH512 are considered just feasible. However, for an attack the target would have to re-use the DH512 private key, which is not recommended anyway. Also applications directly using the low level API BN_mod_exp may be affected if they use BN_FLG_CONSTTIME. Fixed in OpenSSL 1.1.1e (Affected 1.1.1-1.1.1d). Fixed in OpenSSL 1.0.2u (Affected 1.0.2-1.0.2t).

• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.