The CombinedMult function in the CIRCL ecc/p384 package (secp384r1 curve) produces an incorrect value for specific inputs. While ECDH and ECDSA signing that rely on this curve are not impacted, an erroneous calculation in CombinedMult could compromise any operation that uses this routine, potentially leading to data integrity or authentication failures.

Affected systems include any applications that incorporate Cloudflare's CIRCL cryptographic library, specifically versions of the ecc/p384 implementation prior to v1.6.3. The bug was fixed in CIRCL version 1.6.3, so all earlier versions are vulnerable.

The vulnerability carries a CVSS score of 2.9, indicating low severity, and an EPSS score of less than 1%, reflecting a very low likelihood of exploitation. It is not listed in CISA's KEV catalog. No direct attack vector is documented; exploitation would likely require an attacker to supply inputs that trigger the incorrect computation and rely on the consumer of CombinedMult to misinterpret the result. Consequently, the immediate risk to systems remains minimal but warrants patching to eliminate potential integrity issues.