CVE-2026-53398

A flaw was found in the Linux kernel's Network File System Daemon (NFSD). The nfsd4_decode_secinfo_no_name() function does not properly initialize a pointer (sin_exp) before processing an incoming data stream. If the data stream is malformed or truncated, the uninitialized pointer can retain stale data from previous operations. This can lead to an improper cleanup operation, potentially causing system instability or a denial of service.

A flaw in the Linux kernel's Network File System Daemon (NFSD) has been rated by Red Hat Product Security as having an impact of IMPORTANT. When the NFSv4 server decodes a truncated or malformed SECINFO_NO_NAME operation, nfsd4_decode_secinfo_no_name() returns an error before the sin_exp pointer is initialized. Because the inline iops argument buffer is no longer cleared between RPC calls, sin_exp can retain stale contents from a previous operation, and the error cleanup path then calls exp_put() on that stale pointer. Successful exploitation of this flaw can cause a kernel panic, resulting in a denial of service of the NFS server. Affected Red Hat products include Red Hat Enterprise Linux 9 and 10 (kernel and kernel-rt) and Red Hat In-Vehicle OS 2 and 2.1 (kernel and kernel-ivos-qualcomm), for which fixes are being pursued. Older Red Hat Enterprise Linux streams (RHEL 7 ELS, RHEL 8, and RHEL 9.2) are not affected because the vulnerable code is not present in those releases, and affectedness for RHEL 6 ELS is still under evaluation. Red Hat's severity rating of IMPORTANT (CVSS 3.1 score of 7.0) is lower than the CRITICAL rating (9.8) in the upstream CVE record; Red Hat's scoring reflects a more constrained attack vector, higher attack complexity, and privileges required compared with the upstream record's network, unauthenticated, low-complexity assumptions.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.