CVE-2026-63886

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the iSCSI target component of the Linux kernel where the chap server compute hash() function fails to validate the length of the CHAP R parameter before performing a base64 decode. The function allocates memory for client digest based on the digest size, but chap base64 decode() may write more bytes than allocated if the input length is excessive. For example, with SHA-256, the client digest can be overflowed by 63 bytes, and for MD5, by 79 bytes. This occurs because the length check is performed after the write operation has already taken place.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.