The vulnerability is an out‑of‑bounds write that occurs in Bouncy Castle LTS’s native ARM SHA3 / SHAKE implementation when the restoreFullState routine processes a crafted encoded state. Based on the description, it is inferred that the attacker would need to supply such a crafted state to trigger the overflow, allowing the written data to overwrite adjacent memory. The flaw only manifests when the application accepts memoable SHA3 / SHAKE states that may come from untrusted sources, and the CVE description does not confirm any exploit for remote code execution.

Affected products are Legion of the Bouncy Castle Inc.’s Bouncy Castle LTS bcprov‑lts8on running on ARM architectures. All releases from 2.73.0 up to and including 2.73.12.0 are vulnerable; the problematic code is fixed in 2.73.12.1 and later versions.

The CVSS score of 1.7 indicates a low base severity, and the EPSS of less than 1% shows a very low likelihood of active exploitation. The vulnerability is not listed in CISA KEV. Based on the description, it is inferred that the exploit requires the attacker to supply a crafted state to the restoreFullState function, which typically occurs via user‑controlled input such as data received over a network or other external interface. Because the flaw results in an arbitrary memory write, it could compromise data integrity or cause a crash, but the CVE description does not confirm any exploit for remote code execution. The overall risk depends on whether the decryption routine is exposed to unauthenticated input.