During RSA public key initialization from DER or PEM data, a failed BoringSSL decoding triggers a double‑free of the EVP_PKEY* pointer: one release occurs in the catch block and another in the deinitialiser. This double release results in a dangling pointer and eventually crashes subsequent memory allocations, causing the application to terminate. The weakness is a classic double‑free (CWE‑415) and can be triggered by supplying malformed or malicious key material. An attacker who can supply such input to an application using swift‑crypto can force the app to crash, leading to a denial of service.

Apple’s swift‑crypto library is affected. Versions prior to 4.5.1, which handle RSA public key parsing from DER or PEM bytes, are vulnerable. Any app, service, or framework built with these library versions and that accepts or processes external RSA key material is at risk.

The CVSS score of 7.5 indicates a high severity, while the EPSS score of less than 1% suggests a very low chance of widespread exploitation. The vulnerability is not currently listed in the CISA KEV catalog, implying no public exploitation has been reported. Based on the description, the likely attack vector is the ability to supply malformed key data to the library, which is feasible in both web services that accept key uploads and local applications reading key files. A successful exploit would simply crash the process, denying service to legitimate users.