This vulnerability is a padding oracle flaw in wolfSSL’s PKCS7 ciphertext‑block chaining decryption routine. An attacker can submit multiple crafted ciphertexts to the vulnerable decryption function and, by observing the decryption responses, recover the original plaintext. The weakness is a classic padding oracle (CWE‑354) that allows plaintext disclosure, the primary impact of this flaw.

The flaw affects older releases of the wolfSSL library. Any system that incorporates a wolfSSL version prior to the security update that validates interior padding bytes within PKCS7 CBC decryption is susceptible. The vendor listing indicates only “wolfSSL:wolfSSL” as the affected product with no specific version range provided, so the risk applies to all non‑patched instances.

The CVSS score of 6.3 denotes a moderate severity vulnerability. No EPSS score is available, and the issue is not catalogued in CISA’s KEV list. The most probable attack vector is remote, as an adversary can send arbitrary ciphertexts to the decryption endpoint. With access to the target’s decryption routine, an attacker can iteratively recover secrets or sensitive messages, potentially compromising confidentiality across the affected system.