Out-of-bounds Read

Summary

The vulnerability involves the use of low-level GF(2^m) elliptic curve APIs with untrusted explicit values for the field polynomial, which can result in out-of-bounds memory reads or writes. The affected APIs include "EC_GROUP_new_curve_GF2m()", "EC_GROUP_new_from_params()", and various "BN_GF2m_*()" functions. While out-of-bounds memory writes could lead to application crashes or even potential remote code execution, the likelihood of a vulnerable application is considered low. This is because protocols that employ Elliptic Curve Cryptography generally use "named curves," or if explicit curve parameters are supported, they rely on X9.62 encoding, which does not permit problematic input values. X9.62 encoding is also used for ECC keys in X.509 certificates, making the occurrence of problematic inputs in that context unlikely. Applications utilizing "exotic" explicit binary (GF(2^m)) curve parameters that allow the representation of invalid field polynomials with a zero constant term may encounter abrupt termination due to array bounds violations. While remote code execution cannot be easily ruled out, it remains a less likely scenario. The vulnerability affects openssl versions 1.0.2-x prior to 1.0.2zl, 1.1.x prior to 1.1.1zb, 3.0.x prior to 3.0.16, 3.1.x prior to 3.1.8, 3.2.x prior to 3.2.4, 3.3.x prior to 3.3.3, and 3.4.x prior to 3.4.0.